Why compile CAD Lisp?
Lisp is interpreted. So compiling is a bit misleading here, it does not offer substantial changes, it remains interpreted. But what does compiling offer? Files will be encrypted and slowing down elements like spacers are removed.
How to compile?
Compiling for BricsCAD can be done with DEScoder.exe, see your BricsCAD installation under Program Files. The beauty is simplicity here.
For AutoCAD... Start LISP IDE, then... Do something like
(vlisp-compile 'st "C:\MyLisp\Example.lsp" "C:\MyLisp\Example.fas")
"Security through obscurity"
People don't like to talk about decompiling LISP and feel save when files are encrypted.
The truth: Do talk about decompiling and reverse engineering and yes, encryption is weak and not save!
Items are even removed from Autodesk fora. Positioning decompiling as "Better not to be discussed in public" is a joke and doesn't help much. Message for these people: Suppose we talk about your bank account's encrypted data exchange instead of Lisp and reconsider please.
If weak encryption is a problem, then improve the encryption, period.
In fact, it is not hard to decompile. Encryption is not much more than just an obstacle. For BricsCAD, encryption is stronger but the chain is as weak as, so don't expect your code to be save. See for example http://www.sporaw.com/work/decompilers.htm, or https://lispbox.wordpress.com/2014/12/23/visual-lisp-vlxfas-and-visual-basic-v5v6-files-decompiling-procedure/, http://cd.textfiles.com/unprotect/AUTODC/, to wake you up.
And for those that lost their source code, decompiling can be a welcome solution.
So, in order to end this discussion: Who does not want to know what computer virus is embedded in that .fas file? Do yourself a favour and do decompile files from sources of which you are not absolutely sure. Company policy could even be to mark .vlx, .fas and .des as potentially harmful.