I would suggest going to
crucial.com and run their analyzer for your system. If you can add memory at a reasonable price, that's a good option.
Look at your page file. Most systems default to 'let windows manage it for me'. Set a static min and max size instead and it won't constantly be trying to resize.
If the problem started about 8 months ago, you may have installed some software that set itself up as a startup program, possibly with some companions. Run msconfig and check what's loading at startup. Uncheck questionable programs, one at a time, reboot, and see if you notice any difference.