diff --git a/glow/src/quad.rs b/glow/src/quad.rs
index 16bfb25b..fd1deb97 100644
--- a/glow/src/quad.rs
+++ b/glow/src/quad.rs
@@ -150,19 +150,14 @@ impl Pipeline {
 
             unsafe {
                 tagged_instances.clear();
-                tagged_instances.extend(
-                    instances[i..end]
-                        .iter()
-                        .map(|v| {
-                            [
-                                QuadWithQPos(*v, pos_map[0]),
-                                QuadWithQPos(*v, pos_map[1]),
-                                QuadWithQPos(*v, pos_map[2]),
-                                QuadWithQPos(*v, pos_map[3]),
-                            ]
-                        })
-                        .flatten(),
-                );
+                tagged_instances.reserve((end - i) * 4);
+
+                for quad in instances[i..end].iter() {
+                    tagged_instances.push(QuadWithQPos(*quad, pos_map[0]));
+                    tagged_instances.push(QuadWithQPos(*quad, pos_map[1]));
+                    tagged_instances.push(QuadWithQPos(*quad, pos_map[2]));
+                    tagged_instances.push(QuadWithQPos(*quad, pos_map[3]));
+                }
 
                 gl.buffer_sub_data_u8_slice(
                     glow::ARRAY_BUFFER,