How do I find (from a script) the cpu usage of any and all of my module scripts running both on client and server?
It is impossible to find the cpu usage of all your module scripts in your game.
There is no built in way to measure this. Even if you only ran your module scripts, by default you have all the core Roblox scripts so it wouldn’t be accurate
Why do you need to know the cpu usage? If we know why we may be able to suggest something different.
If you’re concerned about computational performance, the microprofiler is the right tool. This will give you the specific information you want about what particular tasks are taking up computation.
To make the microprofiler, which was mentioned above, even more informative, you can time specific parts of your code using the Lua profiling API. Add in profile groups to your modules and the microprofiler will show your code in its reporting.