Performance analysis

[pitag-ha]

There are two (probably) unrelated things in the driver's performance that I'd like to understand:

• Why do very simple AST passes take so long? E.g., for drivers containing derivers, why do the AST passes turning off the warnings w32 and w60 take so long?
        - [ ] Look for a non-IP sensitive example where those passes take long.
        - [ ] Rewrite them using compiler-lib's AST traverse workflow via records.
        - [ ] Compare the two timing results: standard Ppxlib traverse workflow via classes vs compiler-lib's records workflow. Is there a significant difference?
• In some very dubious cases of PPXs, the number of AST passes varies strongly depending on which syntax is used in the AST the PPX is run on. How can that happen?
        - [ ] Reproduce this.
        - [ ] Find an explanation to find out whether that's dubious PPX behavior or a Ppxlib performance bug.