Although your IE shortcut might be in the recycle bin, you'll still want to have IE installed for those special sites that only support IE...

Do you usually have a lot of tabs open? By default, Firefox updates the file which stores open windows and tabs every 15 seconds. The larger this file gets, the longer this takes. A major overhaul was made for Firefox 25 to make this more efficient, so this might not be your issue, but you can stretch the interval out to 60 seconds and see whether that makes a difference. Here's how:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box that appears above the list, type or paste session and pause while the list is filtered

(3) Double-click browser.sessionstore.interval and change the value from 15000 to 60000 (this value is in milliseconds: 15000/1000 = 15 seconds, 60000/1000 = 60 seconds). I don't know whether this takes effect immediately or the next time you start Firefox.

Does that help?

If that doesn't make much/any difference, have you set up Firefox Sync?

I think it's fixed, thank you VERY much!

I will reinstall IE, that's a good point :)

Good day to you

I'm glad that helped. Or perhaps in 3 days you'll say it only helped a little bit... maybe update us in a week?

Yes,thank for support.

UPDATE: 3days passed, browser's running smoothly besides the 2second freezing every hour, but no complaining here! Thank you jscher2000 again