Safari Stuttering...help?

rMBP 15"

OS X 10.8.2

Fresh SSD erase and install OS X + update

Installed: BTT and Flash

Safari extensions: adblock

Safari stutters (like a .5 second freeze) every 5 seconds when scrolling, typing, general browsing. The cursor doesn't stutter, neither does sound or streaming video (flash, html5, fullscreen or not). Also, I've noticed it's associated with a graphical bug where if I'm typing, the last 10 characters or so of my typing (probably the characters typed since the last stutter) randomly flash between disappearing and reappearing.

It doesn't always happen. The only fix seems to be quitting Safari relaunch Safari. Any info on the cause or possible fix?