Mac OSX: strange shaking (jitter) of screen
That jitter is pure software. The CSS/javascript are not executing fast enough to prevent a redraw from being noticeable.

You could try reducing the load on the CPU by quitting other apps or just run some instruments on the pages where you see jitter and either block the js that is slow or decide to edit your text elsewhere and then copy/paste it to avoid seeing the constraints being redrawn.

The detailed video was awesome and allowed me to be certain what I was seeing was software.