What websites are you having problems with? What is on those pages? Ads, Clips?

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

It varies on each website. Some websites use 60% of my CPU (YouTube )others only use 20% (This forum).

Safemode did not help unfortunately.

FredMcD said

What websites are you having problems with?
What is on those pages? Ads, Clips?

I gave examples. Though it happens on every website. And since it happens on every site that means there will be ads and videos on some of them.

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

Does this add-on make any difference?.

Flash block {web link} Never be annoyed by a Flash animation again! Blocks Flash so it won't get in your way, but if you want to see it, just click on it

The add-on didn't help. And as I said in my first reply Safe mode doesn't change anything.

https://support.mozilla.org/en-US/kb/firefox-slow-how-make-it-faster

https://support.mozilla.org/en-US/kb/firefox-uses-too-many-cpu-resources-how-fix

https://support.mozilla.org/en-US/kb/firefox-hangs-or-not-responding

I wouldn't have posted this if any of those worked. It prompts you before you post giving you similar problems.

Anyways, I appreciate your help.

You can check for issues caused by plugins.

• set plugins to "Ask to Activate" on the about:addons page ("3-bar" menu button or Tools -> Add-ons -> Plugins)
• plugins are not affected by Firefox Safe Mode

• https://support.mozilla.org/kb/Troubleshooting+plugins