Well, there is the possibility of either English being a second language, or that the OP'er might be young; in either case, a simple reminder of the ToS would be in line, not mindless flaming.
Congratulations on getting higher FPS. Vsync locks framerates to the refresh rate of your monitor (since you specified that it drops your framerate I'm going to assume that your refresh rate is 60 hz). You'll notice that your framerate probably is its highest if you look directly at a wall, and when you look away it drops again. Vsync tries to keep that from happening for a consistent framerate, so while you don't get 90+, you don't get that general quirkiness when it drops into the 60's either. For me, it's about being playable, not achieving the highest framerate possible