YJIT won't help JSON generation because it's all implemented in C (either the stdlib `json`, or `oj` or `yajl` etc. If what is slow is some RUby code like Acti

YJIT won't help JSON generation because it's all implemented in C (either the stdlib `json`, or `oj` or `yajl` etc. If what is slow is some RUby code like Active Model Serializers etc, then maybe it can help a bit there. But yes, generally YJIT works very well on HTML templates because they are compiled as large methods with not a lot of branches.