M249 4x scope lag?

I have been using m249 for over 1000 hours on modded server never had issue with it. Now I cant even shoot with my favorite gun on vanilla or modded. My frame goes from 110 to 40/50. I think its because of the muzzle flash on the gun. A lot of my friend have the same problem as me and I will hope it will be fix as soon as possible :).The only way to fix it is to put a silencer on the m2 and its pretty bad. I love this gun and I want to still be able to play with it in the futur and not lagging as I am lagging at the moment. Video of my perspective: https://www.youtube.com/watch?v=AICc9TnIY18&feature=youtu.be