Tip: Compressing better

NSIS compressing is good, but not the best out there. If you have a big installer, you could try the following to see if you gain anything:
In your script, use "SetCompress off". Now NSIS compression is disabled - you get a very big installer.
Use WinRAR, create a SFX archive. In the comment section, enter:

Setup=mysetup.exe

TempMode

Now use best compression. If you run this SFX, it will extract the installer to a temporary directory, run the installer, and delete it after it finishes. Very handy, and can save you quite some Kb's 😁

The Problem with that is you have to use an program that is not free. And it you use the "SetCompress force" tag, then you can have a smaller exe. This forces NSIS to compress everything. The zlib compression is awesome, but the problem is that HARDLY anyone knows how to use it properly. But try this and it would work.

You also get nice results if you pack the installer with the !packhdr command using UPX. Is squeezes some additional kb out.

I'll try force. Still, I have an installer where it really matters a lot (800 kb with WinRAR and 870 with NSIS). It's because my content is highly compressable.

You don't have to use it if you don't want to. But since I have a (legal) WinRAR licence, I might as well use it.