Startup is likely to be worse, because it typically runs a lot of different code for not long and the JIT might not have enough time to optimize much of that. OTOH the JIT needs to learn what the program is doing, i.e., profile it in a sense, and that has a cost on interpreter speed.
Still these numbers are worse than expected, especially [object validation], so if there is a way to reproduce it'd be great if you can open an issue about it.
Persisting the JITed code is what we think can solve the slower startup entirely: https://www.graalvm.org/graalvm-as-a-platform/language-imple... Also other things mentioned in https://eregon.me/blog/2022/01/06/benchmarking-cruby-mjit-yj...