Revert "Parallelize system updates"

unnecesary as cilk_for's inside update function should spawn
enough threads
This reverts commit 404e976ee8aeda45d9c9d81c8866fce3ebff676c.
Add FPS reporting and make FPS locking optional

FPS locking really restricts concurrency and performance.
VSYNC actually limits FPS to 60FPS anyways causing yields. Turning off
VSYNC will allow FPS of 800+ on my desktop.