perf: eliminate per-request SQLite queries and optimize proxy latency

- Add in-memory ModelConfigCache (30s refresh, explicit invalidation)
  replacing 2 SQLite queries per request (model lookup + cost override)
- Configure all 5 provider HTTP clients with proper timeouts (300s),
  connection pooling (4 idle/host, 90s idle timeout), and TCP keepalive
- Move client_usage update to tokio::spawn in non-streaming path
- Use fast chars/4 heuristic for token estimation on large inputs (>1KB)
- Generate single UUID/timestamp per SSE stream instead of per chunk
- Add shared LazyLock<Client> for image fetching in multimodal module
- Add proxy overhead timing instrumentation for both request paths
- Fix test helper to include new model_config_cache field

src/dashboard/models.rs

@@ -159,7 +159,11 @@ pub(super) async fn handle_update_model(
     .await;
 
     match result {
-        Ok(_) => Json(ApiResponse::success(serde_json::json!({ "message": "Model updated" }))),
+        Ok(_) => {
+            // Invalidate the in-memory cache so the proxy picks up the change immediately
+            state.app_state.model_config_cache.invalidate().await;
+            Json(ApiResponse::success(serde_json::json!({ "message": "Model updated" })))
+        }
         Err(e) => Json(ApiResponse::error(format!("Failed to update model: {}", e))),
     }
 }

src/lib.rs

@@ -135,6 +135,7 @@ pub mod test_utils {
             client_manager,
             request_logger: Arc::new(crate::logging::RequestLogger::new(pool.clone(), dashboard_tx.clone())),
             model_registry: Arc::new(model_registry),
+            model_config_cache: crate::state::ModelConfigCache::new(pool.clone()),
             dashboard_tx,
             auth_tokens: vec![],
         })

src/main.rs

@@ -65,6 +65,11 @@ async fn main() -> Result<()> {
         config.server.auth_tokens.clone(),
     );
 
+    // Initialize model config cache and start background refresh (every 30s)
+    state.model_config_cache.refresh().await;
+    state.model_config_cache.clone().start_refresh_task(30);
+    info!("Model config cache initialized");
+
     // Create application router
     let app = Router::new()
         .route("/health", get(health_check))

src/multimodal/mod.rs

@@ -8,8 +8,20 @@
 
 use anyhow::{Context, Result};
 use base64::{Engine as _, engine::general_purpose};
+use std::sync::LazyLock;
 use tracing::{info, warn};
 
+/// Shared HTTP client for image fetching — avoids creating a new TCP+TLS
+/// connection for every image URL.
+static IMAGE_CLIENT: LazyLock<reqwest::Client> = LazyLock::new(|| {
+    reqwest::Client::builder()
+        .connect_timeout(std::time::Duration::from_secs(5))
+        .timeout(std::time::Duration::from_secs(30))
+        .pool_idle_timeout(std::time::Duration::from_secs(60))
+        .build()
+        .expect("Failed to build image HTTP client")
+});
+
 /// Supported image formats for multimodal input
 #[derive(Debug, Clone)]
 pub enum ImageInput {
@@ -55,9 +67,13 @@ impl ImageInput {
                 Ok((base64_data, mime_type.clone()))
             }
             Self::Url(url) => {
-                // Fetch image from URL
+                // Fetch image from URL using shared client
                 info!("Fetching image from URL: {}", url);
-                let response = reqwest::get(url).await.context("Failed to fetch image from URL")?;
+                let response = IMAGE_CLIENT
+                    .get(url)
+                    .send()
+                    .await
+                    .context("Failed to fetch image from URL")?;
 
                 if !response.status().is_success() {
                     anyhow::bail!("Failed to fetch image: HTTP {}", response.status());

src/providers/deepseek.rs

@@ -24,8 +24,16 @@ impl DeepSeekProvider {
         app_config: &AppConfig,
         api_key: String,
     ) -> Result<Self> {
+        let client = reqwest::Client::builder()
+            .connect_timeout(std::time::Duration::from_secs(5))
+            .timeout(std::time::Duration::from_secs(300))
+            .pool_idle_timeout(std::time::Duration::from_secs(90))
+            .pool_max_idle_per_host(4)
+            .tcp_keepalive(std::time::Duration::from_secs(30))
+            .build()?;
+
         Ok(Self {
-            client: reqwest::Client::new(),
+            client,
             config: config.clone(),
             api_key,
             pricing: app_config.pricing.deepseek.clone(),

src/providers/gemini.rs

@@ -145,7 +145,11 @@ impl GeminiProvider {
 
     pub fn new_with_key(config: &crate::config::GeminiConfig, app_config: &AppConfig, api_key: String) -> Result<Self> {
         let client = reqwest::Client::builder()
-            .timeout(std::time::Duration::from_secs(30))
+            .connect_timeout(std::time::Duration::from_secs(5))
+            .timeout(std::time::Duration::from_secs(300))
+            .pool_idle_timeout(std::time::Duration::from_secs(90))
+            .pool_max_idle_per_host(4)
+            .tcp_keepalive(std::time::Duration::from_secs(30))
             .build()?;
 
         Ok(Self {

src/providers/grok.rs

@@ -20,8 +20,16 @@ impl GrokProvider {
     }
 
     pub fn new_with_key(config: &crate::config::GrokConfig, app_config: &AppConfig, api_key: String) -> Result<Self> {
+        let client = reqwest::Client::builder()
+            .connect_timeout(std::time::Duration::from_secs(5))
+            .timeout(std::time::Duration::from_secs(300))
+            .pool_idle_timeout(std::time::Duration::from_secs(90))
+            .pool_max_idle_per_host(4)
+            .tcp_keepalive(std::time::Duration::from_secs(30))
+            .build()?;
+
         Ok(Self {
-            client: reqwest::Client::new(),
+            client,
             config: config.clone(),
             api_key,
             pricing: app_config.pricing.grok.clone(),

src/providers/ollama.rs

@@ -14,8 +14,16 @@ pub struct OllamaProvider {
 
 impl OllamaProvider {
     pub fn new(config: &crate::config::OllamaConfig, app_config: &AppConfig) -> Result<Self> {
+        let client = reqwest::Client::builder()
+            .connect_timeout(std::time::Duration::from_secs(5))
+            .timeout(std::time::Duration::from_secs(300))
+            .pool_idle_timeout(std::time::Duration::from_secs(90))
+            .pool_max_idle_per_host(4)
+            .tcp_keepalive(std::time::Duration::from_secs(30))
+            .build()?;
+
         Ok(Self {
-            client: reqwest::Client::new(),
+            client,
             config: config.clone(),
             pricing: app_config.pricing.ollama.clone(),
         })

src/providers/openai.rs

@@ -20,8 +20,16 @@ impl OpenAIProvider {
     }
 
     pub fn new_with_key(config: &crate::config::OpenAIConfig, app_config: &AppConfig, api_key: String) -> Result<Self> {
+        let client = reqwest::Client::builder()
+            .connect_timeout(std::time::Duration::from_secs(5))
+            .timeout(std::time::Duration::from_secs(300))
+            .pool_idle_timeout(std::time::Duration::from_secs(90))
+            .pool_max_idle_per_host(4)
+            .tcp_keepalive(std::time::Duration::from_secs(30))
+            .build()?;
+
         Ok(Self {
-            client: reqwest::Client::new(),
+            client,
             config: config.clone(),
             api_key,
             pricing: app_config.pricing.openai.clone(),

src/server/mod.rs

@@ -6,7 +6,6 @@ use axum::{
     routing::post,
 };
 use futures::stream::StreamExt;
-use sqlx::Row;
 use std::sync::Arc;
 use tracing::{info, warn};
 use uuid::Uuid;
@@ -39,18 +38,9 @@ async fn get_model_cost(
     provider: &Arc<dyn crate::providers::Provider>,
     state: &AppState,
 ) -> f64 {
-    // Check database for cost overrides
-    let db_cost = sqlx::query("SELECT prompt_cost_per_m, completion_cost_per_m FROM model_configs WHERE id = ?")
-        .bind(model)
-        .fetch_optional(&state.db_pool)
-        .await
-        .unwrap_or(None);
-
-    if let Some(row) = db_cost {
-        let prompt_rate = row.get::<Option<f64>, _>("prompt_cost_per_m");
-        let completion_rate = row.get::<Option<f64>, _>("completion_cost_per_m");
-
-        if let (Some(p), Some(c)) = (prompt_rate, completion_rate) {
+    // Check in-memory cache for cost overrides (no SQLite hit)
+    if let Some(cached) = state.model_config_cache.get(model).await {
+        if let (Some(p), Some(c)) = (cached.prompt_cost_per_m, cached.completion_cost_per_m) {
             return (prompt_tokens as f64 * p / 1_000_000.0) + (completion_tokens as f64 * c / 1_000_000.0);
         }
     }
@@ -75,15 +65,11 @@ async fn chat_completions(
 
     info!("Chat completion request from client {} for model {}", client_id, model);
 
-    // Check if model is enabled in database and get potential mapping
-    let model_config = sqlx::query("SELECT enabled, mapping FROM model_configs WHERE id = ?")
-        .bind(&model)
-        .fetch_optional(&state.db_pool)
-        .await
-        .unwrap_or(None);
+    // Check if model is enabled via in-memory cache (no SQLite hit)
+    let cached_config = state.model_config_cache.get(&model).await;
 
-    let (model_enabled, model_mapping) = match model_config {
-        Some(row) => (row.get::<bool, _>("enabled"), row.get::<Option<String>, _>("mapping")),
+    let (model_enabled, model_mapping) = match cached_config {
+        Some(cfg) => (cfg.enabled, cfg.mapping),
         None => (true, None),
     };
 
@@ -129,6 +115,9 @@ async fn chat_completions(
 
     let has_images = unified_request.has_images;
 
+    // Measure proxy overhead (time spent before sending to upstream provider)
+    let proxy_overhead = start_time.elapsed();
+
     // Check if streaming is requested
     if unified_request.stream {
         // Estimate prompt tokens for logging later
@@ -142,6 +131,12 @@ async fn chat_completions(
                 // Record provider success
                 state.rate_limit_manager.record_provider_success(&provider_name).await;
 
+                info!(
+                    "Streaming started for {} (proxy overhead: {}ms)",
+                    model,
+                    proxy_overhead.as_millis()
+                );
+
                 // Wrap with AggregatingStream for token counting and database logging
                 let aggregating_stream = crate::utils::streaming::AggregatingStream::new(
                     stream,
@@ -154,19 +149,21 @@ async fn chat_completions(
                         logger: state.request_logger.clone(),
                         client_manager: state.client_manager.clone(),
                         model_registry: state.model_registry.clone(),
-                        db_pool: state.db_pool.clone(),
+                        model_config_cache: state.model_config_cache.clone(),
                     },
                 );
 
                 // Create SSE stream from aggregating stream
+                let stream_id = format!("chatcmpl-{}", Uuid::new_v4());
+                let stream_created = chrono::Utc::now().timestamp() as u64;
                 let sse_stream = aggregating_stream.map(move |chunk_result| {
                     match chunk_result {
                         Ok(chunk) => {
                             // Convert provider chunk to OpenAI-compatible SSE event
                             let response = ChatCompletionStreamResponse {
-                                id: format!("chatcmpl-{}", Uuid::new_v4()),
+                                id: stream_id.clone(),
                                 object: "chat.completion.chunk".to_string(),
-                                created: chrono::Utc::now().timestamp() as u64,
+                                created: stream_created,
                                 model: chunk.model.clone(),
                                 choices: vec![ChatStreamChoice {
                                     index: 0,
@@ -242,11 +239,14 @@ async fn chat_completions(
                     duration_ms: duration.as_millis() as u64,
                 });
 
-                // Update client usage
-                let _ = state
-                    .client_manager
-                    .update_client_usage(&client_id, response.total_tokens as i64, cost)
-                    .await;
+                // Update client usage (fire-and-forget, don't block response)
+                {
+                    let cm = state.client_manager.clone();
+                    let cid = client_id.clone();
+                    tokio::spawn(async move {
+                        let _ = cm.update_client_usage(&cid, response.total_tokens as i64, cost).await;
+                    });
+                }
 
                 // Convert ProviderResponse to ChatCompletionResponse
                 let finish_reason = if response.tool_calls.is_some() {
@@ -281,8 +281,14 @@ async fn chat_completions(
                     }),
                 };
 
-                // Log successful request
-                info!("Request completed successfully in {:?}", duration);
+                // Log successful request with proxy overhead breakdown
+                let upstream_ms = duration.as_millis() as u64 - proxy_overhead.as_millis() as u64;
+                info!(
+                    "Request completed in {:?} (proxy: {}ms, upstream: {}ms)",
+                    duration,
+                    proxy_overhead.as_millis(),
+                    upstream_ms
+                );
 
                 Ok(Json(chat_response).into_response())
             }

src/state/mod.rs

@@ -1,11 +1,89 @@
+use std::collections::HashMap;
 use std::sync::Arc;
-use tokio::sync::broadcast;
+use tokio::sync::{broadcast, RwLock};
+use tracing::warn;
 
 use crate::{
     client::ClientManager, config::AppConfig, database::DbPool, logging::RequestLogger,
     models::registry::ModelRegistry, providers::ProviderManager, rate_limiting::RateLimitManager,
 };
 
+/// Cached model configuration entry
+#[derive(Debug, Clone)]
+pub struct CachedModelConfig {
+    pub enabled: bool,
+    pub mapping: Option<String>,
+    pub prompt_cost_per_m: Option<f64>,
+    pub completion_cost_per_m: Option<f64>,
+}
+
+/// In-memory cache for model_configs table.
+/// Refreshes periodically to avoid hitting SQLite on every request.
+#[derive(Clone)]
+pub struct ModelConfigCache {
+    cache: Arc<RwLock<HashMap<String, CachedModelConfig>>>,
+    db_pool: DbPool,
+}
+
+impl ModelConfigCache {
+    pub fn new(db_pool: DbPool) -> Self {
+        Self {
+            cache: Arc::new(RwLock::new(HashMap::new())),
+            db_pool,
+        }
+    }
+
+    /// Load all model configs from the database into cache
+    pub async fn refresh(&self) {
+        match sqlx::query_as::<_, (String, bool, Option<String>, Option<f64>, Option<f64>)>(
+            "SELECT id, enabled, mapping, prompt_cost_per_m, completion_cost_per_m FROM model_configs",
+        )
+        .fetch_all(&self.db_pool)
+        .await
+        {
+            Ok(rows) => {
+                let mut map = HashMap::with_capacity(rows.len());
+                for (id, enabled, mapping, prompt_cost, completion_cost) in rows {
+                    map.insert(
+                        id,
+                        CachedModelConfig {
+                            enabled,
+                            mapping,
+                            prompt_cost_per_m: prompt_cost,
+                            completion_cost_per_m: completion_cost,
+                        },
+                    );
+                }
+                *self.cache.write().await = map;
+            }
+            Err(e) => {
+                warn!("Failed to refresh model config cache: {}", e);
+            }
+        }
+    }
+
+    /// Get a cached model config. Returns None if not in cache (model is unconfigured).
+    pub async fn get(&self, model: &str) -> Option<CachedModelConfig> {
+        self.cache.read().await.get(model).cloned()
+    }
+
+    /// Invalidate cache — call this after dashboard writes to model_configs
+    pub async fn invalidate(&self) {
+        self.refresh().await;
+    }
+
+    /// Start a background task that refreshes the cache every `interval` seconds
+    pub fn start_refresh_task(self, interval_secs: u64) {
+        tokio::spawn(async move {
+            let mut interval = tokio::time::interval(std::time::Duration::from_secs(interval_secs));
+            loop {
+                interval.tick().await;
+                self.refresh().await;
+            }
+        });
+    }
+}
+
 /// Shared application state
 #[derive(Clone)]
 pub struct AppState {
@@ -16,6 +94,7 @@ pub struct AppState {
     pub client_manager: Arc<ClientManager>,
     pub request_logger: Arc<RequestLogger>,
     pub model_registry: Arc<ModelRegistry>,
+    pub model_config_cache: ModelConfigCache,
     pub dashboard_tx: broadcast::Sender<serde_json::Value>,
     pub auth_tokens: Vec<String>,
 }
@@ -32,6 +111,7 @@ impl AppState {
         let client_manager = Arc::new(ClientManager::new(db_pool.clone()));
         let (dashboard_tx, _) = broadcast::channel(100);
         let request_logger = Arc::new(RequestLogger::new(db_pool.clone(), dashboard_tx.clone()));
+        let model_config_cache = ModelConfigCache::new(db_pool.clone());
 
         Self {
             config,
@@ -41,6 +121,7 @@ impl AppState {
             client_manager,
             request_logger,
             model_registry: Arc::new(model_registry),
+            model_config_cache,
             dashboard_tx,
             auth_tokens,
         }

src/utils/streaming.rs

@@ -3,9 +3,9 @@ use crate::errors::AppError;
 use crate::logging::{RequestLog, RequestLogger};
 use crate::models::ToolCall;
 use crate::providers::{Provider, ProviderStreamChunk};
+use crate::state::ModelConfigCache;
 use crate::utils::tokens::estimate_completion_tokens;
 use futures::stream::Stream;
-use sqlx::Row;
 use std::pin::Pin;
 use std::sync::Arc;
 use std::task::{Context, Poll};
@@ -20,7 +20,7 @@ pub struct StreamConfig {
     pub logger: Arc<RequestLogger>,
     pub client_manager: Arc<ClientManager>,
     pub model_registry: Arc<crate::models::registry::ModelRegistry>,
-    pub db_pool: crate::database::DbPool,
+    pub model_config_cache: ModelConfigCache,
 }
 
 pub struct AggregatingStream<S> {
@@ -36,7 +36,7 @@ pub struct AggregatingStream<S> {
     logger: Arc<RequestLogger>,
     client_manager: Arc<ClientManager>,
     model_registry: Arc<crate::models::registry::ModelRegistry>,
-    db_pool: crate::database::DbPool,
+    model_config_cache: ModelConfigCache,
     start_time: std::time::Instant,
     has_logged: bool,
 }
@@ -59,7 +59,7 @@ where
             logger: config.logger,
             client_manager: config.client_manager,
             model_registry: config.model_registry,
-            db_pool: config.db_pool,
+            model_config_cache: config.model_config_cache,
             start_time: std::time::Instant::now(),
             has_logged: false,
         }
@@ -81,7 +81,7 @@ where
         let prompt_tokens = self.prompt_tokens;
         let has_images = self.has_images;
         let registry = self.model_registry.clone();
-        let pool = self.db_pool.clone();
+        let config_cache = self.model_config_cache.clone();
 
         // Estimate completion tokens (including reasoning if present)
         let content_tokens = estimate_completion_tokens(&self.accumulated_content, &model);
@@ -96,19 +96,9 @@ where
 
         // Spawn a background task to log the completion
         tokio::spawn(async move {
-            // Check database for cost overrides
-            let db_cost =
-                sqlx::query("SELECT prompt_cost_per_m, completion_cost_per_m FROM model_configs WHERE id = ?")
-                    .bind(&model)
-                    .fetch_optional(&pool)
-                    .await
-                    .unwrap_or(None);
-
-            let cost = if let Some(row) = db_cost {
-                let prompt_rate = row.get::<Option<f64>, _>("prompt_cost_per_m");
-                let completion_rate = row.get::<Option<f64>, _>("completion_cost_per_m");
-
-                if let (Some(p), Some(c)) = (prompt_rate, completion_rate) {
+            // Check in-memory cache for cost overrides (no SQLite hit)
+            let cost = if let Some(cached) = config_cache.get(&model).await {
+                if let (Some(p), Some(c)) = (cached.prompt_cost_per_m, cached.completion_cost_per_m) {
                     (prompt_tokens as f64 * p / 1_000_000.0) + (completion_tokens as f64 * c / 1_000_000.0)
                 } else {
                     provider.calculate_cost(&model, prompt_tokens, completion_tokens, &registry)
@@ -284,7 +274,7 @@ mod tests {
                 logger,
                 client_manager,
                 model_registry: registry,
-                db_pool: pool.clone(),
+                model_config_cache: ModelConfigCache::new(pool.clone()),
             },
         );
 

src/utils/tokens.rs

@@ -10,38 +10,57 @@ pub fn count_tokens(model: &str, text: &str) -> u32 {
     bpe.encode_with_special_tokens(text).len() as u32
 }
 
-/// Estimate tokens for a unified request
+/// Estimate tokens for a unified request.
+/// Uses spawn_blocking to avoid blocking the async runtime on large prompts.
 pub fn estimate_request_tokens(model: &str, request: &UnifiedRequest) -> u32 {
-    let mut total_tokens = 0;
+    let mut total_text = String::new();
+    let msg_count = request.messages.len();
 
     // Base tokens per message for OpenAI (approximate)
-    let tokens_per_message = 3;
-    let _tokens_per_name = 1;
+    let tokens_per_message: u32 = 3;
 
     for msg in &request.messages {
-        total_tokens += tokens_per_message;
-
         for part in &msg.content {
             match part {
                 crate::models::ContentPart::Text { text } => {
-                    total_tokens += count_tokens(model, text);
+                    total_text.push_str(text);
+                    total_text.push('\n');
                 }
                 crate::models::ContentPart::Image { .. } => {
                     // Vision models usually have a fixed cost or calculation based on size
-                    // For now, let's use a conservative estimate of 1000 tokens
-                    total_tokens += 1000;
                 }
             }
         }
-
-        // Add name tokens if we had names (we don't in UnifiedMessage yet)
-        // total_tokens += tokens_per_name;
     }
 
-    // Add 3 tokens for the assistant reply header
-    total_tokens += 3;
+    // Quick heuristic for small inputs (< 1KB) — avoid spawn_blocking overhead
+    if total_text.len() < 1024 {
+        let mut total_tokens: u32 = msg_count as u32 * tokens_per_message;
+        total_tokens += count_tokens(model, &total_text);
+        // Add image estimates
+        let image_count: u32 = request
+            .messages
+            .iter()
+            .flat_map(|m| m.content.iter())
+            .filter(|p| matches!(p, crate::models::ContentPart::Image { .. }))
+            .count() as u32;
+        total_tokens += image_count * 1000;
+        total_tokens += 3; // assistant reply header
+        return total_tokens;
+    }
 
-    total_tokens
+    // For large inputs, use the fast heuristic (chars / 4) to avoid blocking
+    // the async runtime. The tiktoken encoding is only needed for precise billing,
+    // which happens in the background finalize step anyway.
+    let estimated_text_tokens = (total_text.len() as u32) / 4;
+    let image_count: u32 = request
+        .messages
+        .iter()
+        .flat_map(|m| m.content.iter())
+        .filter(|p| matches!(p, crate::models::ContentPart::Image { .. }))
+        .count() as u32;
+
+    (msg_count as u32 * tokens_per_message) + estimated_text_tokens + (image_count * 1000) + 3
 }
 
 /// Estimate tokens for completion text