All the other Launcher options are ignored, if you use the custom firefox profile option. This includes the proxy settings from what I've seen. Proxy and useragent I modify in the prefs.js file of the FF profile. However, I'd also like to see the exbrowser's max timeout option work with a custom profile, if possible. By the way, you can set FF to not load images (permissions.default.image to 2 in about:config or prefs.js) or you can create custom filter rules with adblock, to block only certain slow loading elements (like videos, analytics), or for example block only some images and keep a