Timequest and PLL jitter

Note that it's a slippery slope to start padding your numbers, especially when you're not sure why or what values to use. One other point is that I'm certain the part you're testing in the lab is not the worst one in the bin out of the FAB(Process), and isn't at worst case Voltage and Temperature, so it's operating faster than the Slow Model being timed against. So you have 100ps of slack assuming all of these worst case conditions, but you should have quite a bit of slack within the part/s that are acting up. (Under lab conditinos, designs that don't make timing by ~10% are usually run and work fine.) So that being said, and not knowing anything about your design or issues you're seeing, my guess is that's not your problem and you should concentrate elsewhere. (Heck, put a fan next to the part of shoot it with cold-spray and see if that fixed the problem. If it doesn't, it's not a setup issue).