Don't care. Get a GPU that isn't a piece of stuff. I'm sick and tired of people with horrible computers complaining about lag. If my $400 laptop can handle these weapons and your computer can't, you're the problem, not the weapons.
Additionally, the second image uses a larger rendering context. Either that or you cropped one image and not the other. Which I doubt.
Another thing, 30 FPS is quite good. Most console games run at 30 FPS.
On another, on-topic note, the Uber-Minigun is about ready for beta. When it is, I'll let you guys know.