Rather than writing a long technical reply explaining all this, let me just say: Logging is important because the game changes frequently.
What works today, can randomly break from a patch tomorrow, and unless you're logging the important stuff, you won't know why it's broken or what is actually happening. The current stuff that gets logged, is being logged for very specific reasons, usually due to problems of the past that were reported and we weren't able to figure out until we added more logging.
Logging is like insurance, you hate to have to waste money (or in this case performance) on it, but it exists so when things do go wrong, which they eventually will, you'll most likely be covered in being able to handle it. It won't prevent things from going wrong, but it's something you always rather have and not need, than need, and not have.
The current user perspective of Exilebuddy is a result of how Exilebuddy is now at its highest peak since the project was started almost 6 years ago. Quite literally, Exilebuddy is in the best state its ever been in, thanks in large part to ExVault for his job in replacing our core offerings, and the API now supports the most things in the client it ever has. However, this game is a bot developers nightmare, and that's putting it nicely.
It's great your bots are working so well that you'd rather disable logging to get better performance now, but please understand that your situation is only possible because of the logging we've used over the years to understand bugs and problems and how to make things better. We've done multiple performance passes and logging reductions over the years, so there's not much if anything left to remove (once again, other than OldRoutine since it's so old but that's already being redesigned).
Basically, there's not much we can do about this. Replacing all logging code to a different library would break everything and require a big interruption in your start of league botting, which no one wants. There would be no guarantees performance would be better, because the bottleneck is most likely your hardware. Making disabling logging a more exposed feature works against us in being able to troubleshoot issues that arise from all the random game changes that happen. If you could see some of the stuff we have to fix on a regular basis, you'd understand.
That's why things are the way they are and most likely won't change anytime soon. You have the option of disabling it if you want, which plenty of people have asked about over the years and I always give them the answer, or you can look at better hardware for botting, as everyone should be using a nice SSD anyways since that's what this game requires.
Hopefully that makes sense, it's unfortunate there's even more overhead added by logging, but it really is necessary.