LOL, had the same problem with Obj. 277 and though I had tried everything, but not the reserve. My ass, didn't see it for 2 months or so :-D
tried olso vanilla and did excactly the same....slap my face now :-D
Installed modpack again (very few settings) and it now works again.
The problem was solved by a fresh install of WOT. My installation was about 1½-2 year old
I got the frame rate problem after update to v.9.17.0.1 #10 (24-12-2016) from v.9.15.something. Dropped to about 20 after the normal 75-100. I have never enabled the XMQP but the other XVM settings.
After a couple of troubleshooting session, I decided to unistall the game and Install a vanilla version without mods. I now have about 50 fps but miss my mods. I will not install mods before I know the problem is solved.