Have you cleaned it out at any point? With Macbooks, dust seems to be a pretty common issue after some time, and cleaning it out can make a big difference. Chip

Have you cleaned it out at any point? With Macbooks, dust seems to be a pretty common issue after some time, and cleaning it out can make a big difference. Chips don't slow over time, and if the RAM is good and the HD is good, and you didn't install a bunch of new, hungrier, software, then it could be thermally related. Both removing dust and possibly applying new thermal paste can help.