So I was talking about it to [gm]Orange yesterday.
Here is the new vga bug that often happens to drop your fps to zero or crash your game. I call it “The black sparks from death”:
With and without optimization:
Huge fps drop:
Hope to get detailed info. of your desktop 
Interl® Core™ i7-2600 CPU @ 3.40GHz 3.70 GHz
(RAM) 8,00 GB
Win10 64bits pro
(video) GTX 560 TI 1024mb
Mother b. gigabyte ga-z68ma-d2h-b3
