Few solutions has helped in my case:
- just switch to old GMail version - it sounds like a joke
- turn off HTML Validator extension (HTML Validator also slows browsing, which should have been obvious for me)
- or advanced configuration (check it out below)
- check also other extensions
- UPDATE
Other add-ons which can bother GMail:
- FIREBUG
- Web Developer
Advanced configuration HTML Validator Firefox extension (as an example).

Go to ‘Add-ons’ (Tools -> Add-ons or type Ctrl+Shift+A), find Html Validator and click on ‘Options’ button.
Then disable ‘validation in the Browser’ option.
You can also click on ‘Exceptions’ button and add ‘google.com’ domain.
When it does not help you, just check other plugins.
Advanced configuration FIREBUG Firefox extension
One way is to disable FIREBUG at all and turn on only when you need it. It is pretty easy to do that. Just click on its red icon in the bottom of the Firefox and open FIREBUG. Now you have main FIREBUG’s window. Just click the bug icon in the top left corner and select ‘Disable Firebug’.

After that Firebug’s icon will be gray. When you need use Firebug again, just click the gray icon and open Firebug’s icon. You will have few options to choose.
As you see you can turn off Firebug completely or enable on particular website only.
Another way to manage Firebug is by selecting Tools from main menu -> Firebug. You will have full options.


I disagree with some of your details, but your main point got me thinking. It actually reminds me of some spyware that my spyware removal program just can not get rid of….
harddisk crash…
I found your post comments while searching Google. Very relevant especially as this is not an issue which a lot of peaople are conversant with….
My Firefox working good when i face crash problem then I use your useful tips..