One thing you can do with the finished Lox (or Monkey, if you prefer WACIG) before going into the world of intermediate representations is implementing a peephole optimizer. You look for reducible patterns in the bytecode, and replace them with optimized bytecode. You can also look for certain patterns and replace naive implementations with native builtins/intrinsics. You can work with the raw bytes of the bytecode, so you don't need to introduce an IR just yet.

The Apex compiler at Salesforce does a vast majority of its optimizations as peeps.

EDIT: I _just_ wrote another comment to someone asking similar questions a few days ago. Here's a link to the parent question, check out my thoughts as well as others in the thread. https://news.ycombinator.com/item?id=36119915