Add recent category (game name) selection in start stream menu.
I think most players will switch around games for playing/streaming. Having to manually search and and change the game name (category) every time I switch a game is a bit slow. Twitch Studio can help remember the "recently played" games and allow us to quickly select game from that list. This should speed things up a bit.
When selecting a Category in Stream Info add a tab or a second list for preset Titles and Games for people who switch games constantly. Also adding the ability to change quick stream details in the panel like Title and game without covering the screen. Or even just making a new panel with all the details and a tab with a list of preset Titles and games for fast swapping.