What do you do if your computer is running slowly

If your computer has suddenly started running slowly while performing task that it usually does much quicker then you may have picked up a virus or spyware somewhere and should scan your computer. If you do not have anti-spyware/malware/virus protection you can download free software such as Avast(basic/free edition), Malwarebytes' Anti-Malware, and Spybot Search & Destroy.
If it is not slow because of viruses/malware/spyware, then it may be because the program/s you are running are very memory intensive or you are running a lot of programs at the same time. Make sure that your software meets the minimum system requirements for the program/s you are running, ie. processor speed, RAM amount, video card, etc. Buying more RAM memory may help, or if you are not willing to or able to install more, you can try closing down any open applications that you don't need at that time (if there are any) to free up memory.