You need to start by removing as much "bloat" from the computer as possible.  Unused programs is a good place to start.  Then I use Malwarebytes to scan for anything nefarious.  CC cleaner is a good one as well.  Figure out what programs are running in the background and if they are necessary.  I only run the standard Microsoft security software.  If you can upgrade to 16gb of memory it will help a lot as well.