Reproduction steps:
1. Open the "UISlowDownTest.zip" project.
2. Open the "TestScene" scene
3. Play the scene
4. Hold UP arrow for a couple of seconds
-The Editor freezes and memory starts increasing

Expected result: Objects in the canvas can be transformed without editor freezing
Actual result: Objects being transformed in the canvas freezes it

Note: Just before the freeze profiler shows a spike in Canvas.RenderOverlays.Waitingforjob

Reproduced on: 5.5.0b5, 5.4.1p2, 5.3.6p4, 5.2.5f1