Short screen freeze on Play Level in Viewport

After upgrading to 5.4 I experience a brief screen freeze each time I Play in Editor.
Same when I I hit the play > or Alt-P or Play from From Here. The level will start, mouse gets Look camera control for an instant, then the screen freezes for 1 or 2 seconds before returning to normal. This is happens in even in a fresh empty level. Never happened in earlier version of UE. Hope there is a simple fix.

WIn 10 Pro
AMD Ryzen 9 5950X
RTX 3090