Bad Editor memory leak

Since updating to 5.6.1f1 I'm getting a bad memory leak in the editor.
I run my game and everything is fine, then in scene view I search for something like "t" and the memory use on my PC instantly jumps up to 99% used.


If I look at task manager, Unity is barely using any memory, but all the values combined don't nearly use 99% of my 16GB:



So for some reason, the memory that Unity is using doesn't get assigned to any item in task manager.
While it is sitting at 99% the PC is barely functional.

I know it is Unity because as soon as I close it, this happens:



I confirmed on a colleagues machine that it does the same.
It seems to also happen without the game running, but to a much lesser extent.

 

There's a known issue involving the preview window when searching for items.
https://forum.unity3d.com/threads/c...-5-6-0-p4-crashing-unity-all-the-time.470756/