Explore skipping the metaschema check for vendored schemas #723

Looking at a profile under Tachyon to try it out, it looks like we spend a significant amount of time for trivial instances on non-trivial schemas running through metaschema validation (check_schema).

It may be worth skipping the validation, which requires some design decisions and exploration.

• Confirm that it's really worth doing / saves significant time
• Ensure that the metaschema gets checked when these schemas are updated in the repo (may already be setup)
• Figure out a good mechanism for conditionally disabling the check

This might merit general exposure as a flag, and having the hooks opt-in to it.