Thank you for your question and reaching out.
I can understand you are facing performance issue with your PC.
As you mentioned there was some Virus infected , I am afraid that it may be infected on your Data folders as well.
In this Case I will advise you to do update Antivirus with latest version and do FULL System Scan including boot sector Scan.
Also , please check your Disk for any potential bad sectors using below command.
chkdsk /f /r C:\
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