I recently had a problem where my hdd was making a lot of noise and was constantly writing while running a Windows install of Apple’s Safari web browser.
What solved it was to go to:
Edit > Preferences then to the Advanced area. Then change the Default space for database storage to something higher than 5MB, in my case I set it to 500MB since I have a lot of RAM.
Another option is to go to:
Edit > Reset Safari
You could also disable any extensions you have running, but I think increasing the database storage is the best solution.