Hi all 
I’m reporting this bug, like the title say, if I’m ingame playing (I mean in a round) and do an ALT+TAB to go on my desktop, then click on the game icon to get back to it, I have huge frame drops, normally I get between solid 110 and 140 depending on map complexity, but with this alt+tab, frames drop to 20-40, just now I had like 10fps 
None of the games I play have this problem, in BF4 for exemple I always alt+tab to chat on battlelog, and the game keeps its solid 90-120 fps.
I have a very clean gaming laptop cause it’s my workstation (design and video). ASUS G75VX, 8Gb RAM, GEFORCE GTX 670 3GB ram overclocked, last geforce drivers + tested older ones, 2 hybrid ssd (16Go). System is on one hard drive, games on the other, both are clean and defragmented, I tested this under 8.1 pro wich is my main system and windows10. Same issue, huge frame drop when alt tab.
Today, I restarted, and the frame drop happened when on the tab interface to report a player.
If I’m on the game interface (barracks) there’s a 50 chance that I do not have frame drop if I alt tab.
The only way to get rid of this problem is to close the game and launch it again.
Thanks devs