I don’t think that is to simulate a slow device, because either my game is very efficient to the point that it can run on 1 megabyte, or the Simulated Memory is something I don’t know what it is. Maybe if Roblox added a CPU cap, it would work?
I would suggest setting a limit on the processing power that Roblox can use while testing. (This only works if you have multi-core CPU, which I assume you have when you described you setup).
Now, I just realized you’re using a Mac after I wrote this guide for Windows, but I’ll keep it for others’ interested.
Unforunately, I couldn’t find an app that does it for you for MacOS, however if you’re computer smart follow what this guide says. It creates a bash script that will ‘slow down’ the process. http://hints.macworld.com/article.php?story=20110131001708255
If you are using Windows and are interested,
Open Task Manager and right-click Roblox Game Client.
Then select Go To Details.
However, you can use nice and renice to lower Roblox Studio’s priority and then run some resource intensive task in the background so Studio doesn’t get as much CPU time. It’s a stupid solution, but it should work…