My laptop is slow

Slow processor.
Not enough memory, you should have a minimum of 2GB for 32-bit windows and 4GB for 64-bit windows.
Slow hard disk, a lot of cheaper laptops come with disks spinning at 4200rpm with a small amount of cache and poor access speeds.
Overheating try blasting fan and vents with compressed air.
HDD may need a defragment.
HDD getting full.
Lots of unnecessary apps being loaded.
Virus, spyware ...