If it's home tower try using belark advisor and see if you can identify your computer mother board then look up specs for memory. Because of new security fixes many computers are sluggish in certain domains. Some sites require less space. If you can max out ram and make sure you have plenty of hard drive space. If your near/at 75% of HDD capacity, the hard drive will slow page file swaps and make it sluggish.
Maxing out memory will help. Cloning your system drive e to larger one can also help . I picked up SATA HDD 1 TB for like $45!