My windows 7 ultimate has slow Is it attacked by Malware

Hi i am robin, i am using Microsoft windows 7 OS on my home system. From last couple of days I am experiencing some performance shift with my windows 7 ultimate. I shared this to my friend he told me your computer might be affected from Malware or Spyware. So I searched about what type of malware remover software is best to regain my original win 7 performance. There are too so much malware fighter software that companies claimed that they are industry best malware remover programs. I got this website so I decided to asked it here about the situation i am facing. Is it attacked by malware or not. Or should i remove or reinstall my windows 7 what you guys say.