Basically this IS WITH VSYNC OFF , whenever there is a message the frame rate dives out... I tested this in the solar system zoomed out..
Smooth as anything to start off with , gave 100 metal to another race came back to the solar system view and the message came up " THANKYOU FOR SUPPORT ". The frame rate dived to about 15-20fps , message clears off the screen frame rates back to 60+. I asked for a trade alliance , message pops up that it was accepted or declined again frame rates dive to 15-20fps message clears frame rates shoot back up again.