perf: improve hiding the ui

src/ui/main-window/ThumbnailsPanel.swift

@@ -52,6 +52,8 @@ class ThumbnailsPanel: NSPanel {
                 completionHandler: { super.orderOut(sender) }
             )
         } else {
+            // orderOut requires WindowServer. Let's hide before calling it, in case it lags
+            alphaValue = 0
             super.orderOut(sender)
         }
     }