Is it a laptop? I'm assuming it is since you're talking about glued screws to the motherboard... does the CPU have turbo boost? Sometimes that can get messed up, forcing the CPU to just overload all the time. Go to the powersettings and change the max CPU usage. First try like 50% to see if it makes any difference, then you can probably leave it at 85-90%.
If it's a desktop, then don't care about the motherboard, just remove the heatsink and clean it from thermal paste (and the CPU!), apply new paste and reattach the heatsink.