delay extension start
My Firefox start slowly. Many topics and discussions talk about how to accelerate, but the main reason is additional custom extensions. I understand very well that Firefox itself start quickly and slowness is because of extension. So to resolve this problem please add a possibility to delay extension start that cause slowness of all Firefox.
Often, customers don't need all extensions with a first second of Firefox start. So add a possibility to delay extension start separately for each extension.
That is not possible as a lot of extensions add elements to the Firefox user interface and hook into specific startup events. If you can identify specific extensions that cause such an issue then try to contact the developer for advice. If you have many extensions then you can consider to disable some or use extra profiles for extensions that you only need for specific cases and not all the time.