Eventually the performance drops as the processor starts throttling and the fans are still at their slowest speed. I installed iStat menus to track the temps and fan speed. I have seen the temp as high as 220 with 2500 rpm fan speed...
Try
resetting the SMC.
The Intel processors used in Macs are designed to automatically shut down to prevent damage if they truly overheat. CPU Tjmax = 105C (221F), GPU Tjmax = 100C (212F) on i3, i5, i7 processors. (Source:
Intel)
Unless there is a rare defect in a Mac, most temps are well within the normal operating range, considering the workload being put on it. Websites with Flash content, games and other multimedia apps will put higher demand on the CPU/GPU, generating more heat. This is normal. If high demands are consistently put on the system, such as gaming or other multimedia tasks, expect temps to rise and fans to spin up accordingly. It's just the Mac doing its job to maintain temps within the normal range.
It is also quite normal for a Mac to become extremely hot to the touch during intensive operations. The aluminum body transfers heat more effectively than other materials used in computer casings, so the heat is more easily felt on surfaces. This doesn't indicate that it's overheating and will not harm the computer to be hot to the touch.
The fans are always on when a Mac is on, spinning at a minimum of 2000 rpm (for MBPs) or 1800 rpm (for MBAs, MBs and minis). iMacs have 3 fans with minimum speeds in the 800-1200 range. They will spin faster as needed to keep temps at a safe level.
If the fans are spinning up without increased heat, try
resetting the SMC.
(PRAM/NVRAM has nothing to do with these issues, so resetting it will not help.)
The intake and exhaust vents are in the back of the computer near the hinge on all Mac notebooks (except the new MBP with retina display, which has intake vents along the sides at the bottom). The iMac vent is a slot on the back near the top of the computer. Make sure the vents remain unblocked to allow the computer to perform at its best.
Learn about the fans in your Mac
Apple Portables: Operating temperature
For Flash-related issues:
