Most of the issues in performance in my game come from local scripts, and although I can view script performance in studio, it would be much more useful to see these stats while I am in an actual game.
Feel free to post any reasons you may be for or against this of course 
I personally would prefer everyone to be able to see it, but I don’t know what problems letting other people see that would bring.
microprofiler already covers this use case better than Lua could. ctrl+f6
It doesn’t show which scripts are responsible for what though, making it less than ideal to track down causes of poor performance.
Detailed view does.
You can even use debug.profilebegin and profileend to mark specific parts of your script in the timeline.
that said, the fact that nobody here knows about that feature indicates that more should probably be done in the way of profiler documentation.
Spotco made a nice video series on it last year–maybe developers would pay more attention if there were text docs to go along with that?
The page is up at http://wiki.roblox.com/index.php?title=MicroProfiler if you haven’t seen it, spread the word
Still waiting for this article to be completed and added officially to the wiki http://wiki.roblox.com/index.php?title=User:MaxV
As someone who is trying to make a detailed game, that has been insanely useful.
I have heard of and used the microprofiler. It’s amazingly useful, but my biggest problem with it is that it only tells you what script caused what performance loss after you open it(If you look in the history when it was not opened it will show all scripts as $script). And honestly the jumble of information it gives me is a lot more than I need most of the time, haha.
But I can see how this is probably my fault for not reading the full documentation - the link @filiptibell posted seems to have a lot more information on what it is actually showing me, and maybe if I can figure more of that out I won’t have as much of a want for this.
I’ve gotten the microprofiler working on mobile in the past, but it’s pretty complicated (current, when set up, it creates a local web server from your mobile device) - Definitely not what we want.
@Seranok may have some specifics on mobile performance tools.