A few things to try before you embark on your journey of x86 -> x64. (32bit to 64bit).
* Delete all your temp files
* clear out your cache in your browser (if it is the browser that is slowing down).
* de-fragment your hard drive
* reboot
See if you still have performance problems or issues. If they still exist are they still as severe or are they reduced?...
What are the symptoms when you see the slow down? are they always in the same program, or are they random?
What version of windows are you using? (Windows 10 Home, Premium, Pro, Windows 8 etc).

