hello puchkov67, sorry but at the moment we can only answer questions in english at support.mozilla.org. if you want to help in russian please visit the forum of the russian speaking mozilla community: http://forum.mozilla-russia.org/

Google translate: Slow loading sites. How to fix it?

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes