The Mozilla Maintenance Service allows Firefox to install updates without requiring you to click Yes in the Windows User Account Control dialog. The service is run "on demand" and will remain stopped until it is needed. When the service is needed, it will be started again for the period of the update. If there are any problems updating through the service, it will fall back to updating the old way via the Windows User Account Control prompt.
The Mozilla Maintenance Service allows Firefox to install updates without requiring you to click Yes in the Windows User Account Control dialog. The service is run "on demand" and will remain stopped until it is needed. When the service is needed, it will be started again for the period of the update. If there are any problems updating through the service, it will fall back to updating the old way via the Windows User Account Control prompt.
You may have activated a lot of add-ons. Each add-on activated will slow down the firefox while opening a new session.