So I have this laptop and after a power surge (it was pluged into the wall) it started to run slowly. To me the power surge seems unreasonable because of the battery. It was running pretty hot before the power surge, but I shut it because of heat. I don’t think it was the heat because it never shut down as if it were running at unsafe tempertures. My thought is the hard drive is failing or the motor in it slowed down but it is not making any unusual noise so even that idea seems doubtful because that wouldn’t happen over night. It is an HP laptop with a core i7 and I have had it for around 4 years. If anyone has any ideas please tell me!
What windows are you running? I would open up task manager or get CPU-Z and see what your clock speed is and check to see if it is normal. For your HDD I would grab SpeedFan or CrystalDiskInfo/HDTune and see if it is dying.
It's possible for a overheated CPU or mobo to go into "safe mode", have had that happen before but it was because of a dead CPU.
Wonder if the computer runs just as slow plugged in as when it's on battery. If different then it's a throttling issue. If it's slow regardless of ac-adapter status, then perhaps it's a hard drive-ish related issue. Maybe the disk is experiencing more than the usual amount of errors ever since the power surge.
I'd run CPU-Z or Speccy and check the clock speed while I messed around with the adapter. Then:
sfc /scannow (just cuz, not really important)
chkdsk /f (then reboot and let it run, important)
After neither of those help, not really sure what the issue is since the symptoms described are either a power issue or a hard drive issue as VXAce pointed out. The benchmarks on the HD are a good idea too.
If you can, install something like HD Tune Pro onto the laptop and run the error test. Then check to see if there are any smart errors. If there are, the hard drive is dying and you either better change it or recover your data while you still have time.