possible perf issues with Jackson 2.17

[pjfanning]

See FasterXML/jackson-module-scala#672 Thanks to @plokhotnyuk for doing the research.

jackson-core has a new buffer recycler default in 2.17 that will cause perf issues for some users.

Specifically, creating lots of ObjectMappers that have not been created using shared JsonFactory instances will likely lead to much worse perf with creating byte and char arrays in Jackson. Jackson 2.16 and before used a buffer recycler based on ThreadLocal whose lifecycle was scoped just to the thread as opposed to the new approach where the buffer recycler lifecycle is scoped to the JsonFactory. If you don't use the same JsonFactory when creating ObjectMappers, then you will get new buffer-recycler instances for every instance of ObjectMapper.

[pjfanning]

I did a quick review of the json4s usage of Jackson ObjectMapper and it looks like the Jackson changes shouldn't have a major impact. It would still be useful to do benchmark checks.