About startlazarus.
When you install Lazarus (running install as admin), the "Lazarus.app" may be installed into a location to which your user has no access.
When you install packages, the Lazarus.app gets rebuild. But as user you may not be able to replace the global installed lazarus.app.
Therefore the new build will be in your user folder ~/.lazarus/
StartLazarus, makes sure the correct lazarus is started.
If you have write access (as the user, who runs/uses Lazarus) to the global install location, then your rebuild happens there. In that case you do not need StartLazarus.
Otherwise you can start the correct Lazarus build from the correct location yourself.
---
I may have missed some details, the above is what happens on Win and Linux. It should be the same on Mac, but I do not use Mac....
There is a StartLazarus.lpi in the IDE folder. You can open the project, and rebuild it.
If you want a small-ish (smaller than otherwise) build, make sure you build without debug info, or strip it.
If you are on windows, ignore the *.app folders.
You will have the exe.
The *.app folders are for Mac users.