I'm not sure that it happens on the dev-branch too, but since 1.54 my fps drops to 0 when burst(massive) shooting happens. Eg. when two ghost hawk shooting each other with miniguns, or AH-9 attack with minigun and i'm near they.
It happens only in MP. I can't reproduce it in the editor with AI.
It's caused by the tracers. When the game generate lot of tracers. This mostly occurred when i'm near the source. If I see tracers from distance(eg. 1km) it's not affect the fps.
LOG:
SuppressCache::Trace called with huge input. Function exited to prevent program stall inside. <COORDINATES>
In last 500 miliseconds was lost another 3 these messages. {F27642} {F27643}