enable release build optimization

[qiweiii]

• due to release build has different behaviour than debug build, I turned off some compiler optimization in fix release build #355 to ensure release build correctness (swift version 6.1.2)
• we should fix it by either locate the code/lib caused the issue or wait for swift updates, then re-enable all optimization

[xlc]

Should try different optimization level, find out which level breaks it, find out all the individual optimizations that are enabled in that level, then disable each of them one by one, eventually we will know which optimization breaks it. Chance are there is already a bug report on Swift compiler otherwise it could be tricky to isolate which code triggers the issue. But at least we can only disable one (or a few) optimizations rather disable all.