Thank you for your question - it's a good one - and I'm happy to say that the performance impact of using Axonator should be negligible.
I currently mention the following in the FAQ - Is there a performance hit when decrypting axonated code? but I'll update the docs on the next release to make it clearer:
There may be a very small hit the first time a function is decrypted, but once done, Axonator caches a reference to the compiled function.
All subsequent calls to the function are routed straight to the cached compiled version, so this small hit is only ever taken the once.
The best way to understanding the real implications is to try it out on a test project. The new AxonatorUI extension makes it easy to encrypt functions and .trio files to try them out.
Go to AxonatorUI Ext
Hope this helps,