To close processes, try using the built-in about:processes page. On Windows, you can open it by pressing Shift+Esc. This allows you to see which tabs are using a lot of memory or CPU. If you see usage on that page that doesn't seem to make sense, let us know what you see and maybe we'll have a suggestion.

See also the about:unloads page.

no, when i check task manager, it still says firefox(14) or a bigger number sometimes

Do you mean the Windows Task Manager has more Firefox processes than are shown on the about:processes list?

i counted everything on it and yes, there is.

Possibly there is a separate/hidden instance of Firefox for some reason (sometimes it's a very bad reason, like malware using your computer for coin mining).

In the Windows 10 Task Manager, if you switch to the "Details" tab, and click the title of the Name column, you can sort all the firefox.exe processes together. Then you can add the Command Line column by right-clicking any column header and choosing "Select columns". What you normally see in this column for firefox.exe is:

(1) Basic startup path like

"C:\Program Files\Mozilla Firefox\firefox.exe"

(2) Spin-off processes that start with

"C:\Program Files\Mozilla Firefox\firefox.exe" -contentproc --channel="...

If you see any processes that do not match that pattern, those may be suspicious.

although that didn't fix the problem, nor is it malware. it did help find which process was taking up a lot of memory. thank you