Blizzards too hurt performance. That's not really a secret, mystery, or really anything. When a blizzard starts, there's simply so many particle effects on screen that it just slows down everyone's system by a fair bit.
The problem is NOT the blizzard concept itself; it's how it's implemented. All relic has to do is add an option to the video settings for "blizzard quality". High should be as it is now, medium should reduce particle count, and LOW needs to replace ALL the particles with a simple screen effect.
Since the screen effect would just be a UI element (probably scaleform), the performance impact would be essentially zero. The only other thing that happens in blizzards is reduced move speed, sight range and cold damage... none of which effect performance.
However, the performance hit really isn't THAT big. Since CoH2 is bad and doesn't support SLI, I can only run on a single GTX570 - a mid range card from late 2010. It's almost three years old at this point. That single GPU can push about 80fps on max settings with no AA, at 1080p.
Drop your settings a fair bit. This is CoH - it's demanding, just like COH1 was on release.
My frame rate doesnt drop below 18 in a blizzard,
18 still causes lag - you should be at a stable 30. Drop your settings lower.