Last time I profiled jq in my particular use case - querying large GeoJSON files - I discovered it spent practically all of its CPU in assert, and it went a lot faster when built with -DNDEBUG, but since I could not rule out that some of its asserts have side effects I went back to the upstream package.

I think beating the performance of jq would be very easy for anyone who set out with that as a goal. It also has its own internal strtod and dtoa which are easily beaten by ryu or C++'s from/to_chars, so I would start there after dumping the weird asserts.