diff --git a/src/taskbar/task.c b/src/taskbar/task.c
index 8895aa9..cf293cf 100644
--- a/src/taskbar/task.c
+++ b/src/taskbar/task.c
@@ -632,6 +632,9 @@ void task_refresh_thumbnail(Task *task)
         cairo_surface_destroy(task->thumbnail);
     task->thumbnail = thumbnail;
     task->thumbnail_last_update = get_time();
+    if (task->thumbnail_last_update - now > 0.01) {
+        fprintf(stderr, YELLOW "tint2: %s took %f ms (window: %s)" RESET "\n", __func__, 1000 * (task->thumbnail_last_update - now), task->title ? task->title : "");
+    }
     if (g_tooltip.mapped && (g_tooltip.area == &task->area)) {
         tooltip_update_contents_for(&task->area);
         tooltip_update();