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

 Now, restart Firefox and see if the problems persist.

Hello Sajibry Have you looked at these articles yet? https://support.mozilla.org/en-US/kb/firefox-uses-too-much-memory-ram https://support.mozilla.org/en-US/kb/firefox-uses-too-many-cpu-resources-how-fix you should try to disable hardware acceleration and see if it helps any. Firefox has hardware acceleration set to "on" by default, but it's still young, which means some video cards or drivers might have problems with it. You can try to disable hardware acceleration to see if that alleviates your problems. You might need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.). Then perform these steps for Firefox version 29.0 and above: Click the menu button New Fx Menu and select Options for Windows or Preferences on Mac or Linux. For Firefox 28.0 and previous versions, click the orange Firefox button at the top left, then select the "Options" button, or, if there is no Firefox button at the top, go to Tools > Options. In the Firefox options window, click the Advanced tab, then select "General". In the settings list, you should find the Use hardware acceleration when available checkbox. Uncheck this checkbox. Now, restart Firefox and see if the problems persist.