Slow computer performance may be caused by following reasons:
1, virus or malware, on this circumstance, you should run a full scan with your anti-virus program.
2) Too much junk files or temporary files. On this condition, suggest you optimize your computer. For optimization tool, I would like recommend ccleaner, and Cloud System Booster.
3) No Enough Memory. You need to increase the virtual memory.
4) Poor Internet Connect Speed. he slow network will lead your surfing slow, which you may feel your laptop slow. You need to speed up your internet.
You can also take the optimization tool Cloud System Booster to fix the problem for you.