https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/websites-look-wrong-or-appear-differently

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

You can check the server response in the Network Monitor.

• https://developer.mozilla.org/Tools/Network_Monitor

Ok i will delete unwanted bookmarks

Try deleting your search history since having a lot of history tends to cause these kind of problems.

i don't have a lot of history because i deleted often so it was not a problem i think the website have a issue or i am using adblocker the website have a lot of ads so that it hangs

As a test, Load the web page. After the page is loaded, click the down arrow next to the AdBlock icon. Now select Disable on <web site>.

why this videos not supported

What happen if the downloads are failed in midway is that firefox delete hole file are it was left in drive

very slow i don't have many taps just two taps it hanging again and again i really hate it

That is about the HTML5 media player. Windows XP doesn't have built-in support for playing MP4 files and Firefox relies on built-in OS support to play media files via the HTML5 media player, so you are likely out-of-luck when only the HTML5 media player can be used to play the media file and not a plugin based player like the Shockwave Flash plugin.

• [/questions/1053509] MP4 files won´t play

You can use an extension to switch between the Flash player and the HTML5 media player on the YouTube website. YouTube Flash Video Player:

• https://addons.mozilla.org/firefox/addon/youtube-flash-video-player/