Here are few of my improvement ideas for Tor Browser (and releated):
* add more possible proxy hosts * make that TOR probes very often all avaliable hosts and pick every time the fastest one to prevent lagging while sites load
* add a module with discovers the site load time and it determine that it's (or it's content) load to slow then would self switch proxy for the site to make it load faster
* don't make tor browser install by default the No-Script plugin because it's preventing sites from working correctly (and it's very annoying to unblock each time scripts for each page, site or server)
--- Mcgiwer