FPS drop only when Widget BP open on background


I’m having a strange issue.

My project runs fine, until I open the Widget BP.

Once any Widget BP is opened as background window from the editor (a used one for the project, or a totally new and empty Widget BP) my fps is droping in 2 cases

  • When i’m in editor and I pass the mouse over the Project Viewport.

  • When I launch Play Mode.

In both cases I loose between 15 to 20 fps.

I’ve tried to disable widget, to delete it from the begin play create widget node… The most strange is that even a newly empty created widget gives that drop in performance.

Note that this is happening only in one project, the others don’t have that issue.

Any help would be appreciated.