Slow frame rate with two editors?

I need to run two copies of the editor while working on network features of my game. Whichever one the foreground app runs at 30-40 fps, but the other one runs at 2-4 fps.

I have turned OFF “Editor Preferences|Miscellaneous|Use Less CPU when in Background”. Is there anything else I can do to improve the performance of the editor session when in the background?