It would help to know which program is giving you that message. My post here applies to Firefox but much the same could apply to other programs as well:
http://www.theanswerbank.co.uk/Technology/Question1492287.html
I'll add to that by further suggesting that you run a malware scan, using the free version of Malwarebytes, as malware is well-known for hogging a computer's resources:
https://www.malwarebytes.com/antimalware/
(NB: If you need to download and install the program, note that you'll encounter a pre-ticked box offering you a free trial of the Premium version. Remove that tick before proceeding further).