timingTest is kind of self explanatory; it's a timing test :)
It basically runs a code on all of your cores and see if they're synced up. If they are, it passes the timing test. If it fails, it gives you a timingTestError. When the game gets one of these, your game will fall back to a "safe" low-resolution timer so that these unsynced cores won't kill the game. You'll hit issues like your framerate being capped out at 64 (since the game refreshes 64 times a second on he low timer) but that's about it. If you force a high resolution timer on an unsynced processor, you'll get really odd timing issues like your cooldowns finish or never finish before they should be, your projectiles will move at really fast or slow rates, you won't turn right, and so on.