diff --git a/rtiow/src/renderer.rs b/rtiow/src/renderer.rs
index ba26d43..db21b8f 100644
--- a/rtiow/src/renderer.rs
+++ b/rtiow/src/renderer.rs
@@ -256,11 +256,13 @@ fn render_worker(
 }
 
 pub fn render(scene: Scene, output_dir: &Path) -> std::result::Result<(), std::io::Error> {
-    let (pixel_req_tx, pixel_req_rx) = channel::unbounded();
-    let (pixel_resp_tx, pixel_resp_rx) = channel::unbounded();
+    let cpus = num_cpus::get();
+    let (pixel_req_tx, pixel_req_rx) = channel::bounded(2 * cpus);
+    let (pixel_resp_tx, pixel_resp_rx) = channel::bounded(2 * cpus);
 
     let scene = sync::Arc::new(scene);
-    for i in 0..num_cpus::get() {
+    println!("Creating {} render threads", cpus);
+    for i in 0..cpus {
         let s = sync::Arc::clone(&scene);
         let pixel_req_rx = pixel_req_rx.clone();
         let pixel_resp_tx = pixel_resp_tx.clone();
@@ -271,12 +273,15 @@ pub fn render(scene: Scene, output_dir: &Path) -> std::result::Result<(), std::i
     drop(pixel_req_rx);
     drop(pixel_resp_tx);
 
-    for y in 0..scene.height {
-        for x in 0..scene.width {
-            pixel_req_tx.send(PixelRequest { x, y });
+    let (w, h) = (scene.width, scene.height);
+    thread::spawn(move || {
+        for y in 0..w {
+            for x in 0..h {
+                pixel_req_tx.send(PixelRequest { x, y });
+            }
         }
-    }
-    drop(pixel_req_tx);
+        drop(pixel_req_tx);
+    });
 
     println!("Rendering with {} subsamples", scene.subsamples);
     let mut img = RgbImage::new(scene.width as u32, scene.height as u32);