Are you recording gameplay to a hard drive? Because if you're doing that, you are probably being slowed down by hard drive write speeds.
Recording will almost always slow down gameplay somewhat, but drops like that indicate that something else is going on, like a hard drive bottleneck. Probably doesn't have anything to do with your GPU unless you have run into a vram limitation (which is highly, highly unlikely).
Yeah but when I used to record (like 1 week ago) it was fine, no issues.