Here is a suggestion or two.
1. Onyx is a piece of software that will delete temp files and such. It's free
2. AVG has a Mac version of their software but I don't recommend it. Consider ClamXAV if she really feels the need for Anti-Virus software. Currently there are no virus's active against OS X that are in the wild. There is a little Malware though.
3. Consider increasing the amount of RAM in the machine
4. Cookies can be deleted in Safari Preferences
5. Use canned air to blow out the cooling vents.
6. Check to see how much hard drive space is available. A disk that is getting full will slow the machine down.
7. Run Disk Utility, it's in the utilities folder which is inside the applications folder, to see if the disk itself has problems. If it does, replace it.
8. Be prepared to hear that the drive is about to shuffle of this mortal coil. Make backups of the important stuff. Of course, you already do that........
That should keep you going for a while.
Let us know how you get on.
My daughter has an older MacBook from 2008 or 2009 with OS version 10.58. It's running VERY slowly.
I have a PC and when mine runs slowly, I can easily delete temp files, delete history, delete cookies, etc. using buttons on my PC. She has not found a way to delete similar stuff on her Mac, and I don't know how to advise her. Can anyone supply a few steps she can take to get rid of all that stuff that may be slowing her down?
Also, I've suggested AVG and a few other free antivirus/antimalware programs, but she has checked and says they can't be downloaded because her OS is too old. Does anyone know of a similar free program that would work on her Mac Book? She's not working right now so can't afford to buy a new one. Many thanks! BTW, she is even more a "newbie" than I am...