As someone who has worked has written parsers & worker with generated parsers, to add to what OP has said about performance, from my experience there is a lot of noise that comes from a generated parser, and interacting with the code/output is quite unpleasant.

Also you have to decide on checking in garbage generated code into your source or adding a build step so you don’t check the code in (which is less trivial for certain languages/stacks).

Unless I’m making an MVP or a prototype I would write the parser. It’s not as hard as it sounds