--- a/gfx/wr/webrender/src/render_task.rs
+++ b/gfx/wr/webrender/src/render_task.rs
@@ -210,19 +210,23 @@ impl RenderTaskGraph {
             tasks: &[RenderTask],
             task_id: RenderTaskId,
             task_depth: i32,
             task_max_depths: &mut [i32],
             max_depth: &mut i32,
         ) {
             *max_depth = std::cmp::max(*max_depth, task_depth);
 
-            {
-                let task_max_depth = &mut task_max_depths[task_id.index as usize];
-                *task_max_depth = std::cmp::max(*task_max_depth, task_depth);
+            let task_max_depth = &mut task_max_depths[task_id.index as usize];
+            if task_depth > *task_max_depth {
+                *task_max_depth = task_depth;
+            } else {
+                // If this task has already been processed at a larger depth,
+                // there is no need to process it again.
+                return;
             }
 
             let task = &tasks[task_id.index as usize];
             for child in &task.children {
                 assign_task_depth(
                     tasks,
                     *child,
                     task_depth + 1,