Consider internally representing identifiers from globals and class fields as unique numbers

This could potentially speed up hash map access for these values, since we can just key off the number rather than the identifier string.

We could use some incrementing number as we compile the code. We shouldn't use the hash values of the strings, since those could collide.

The issue names no files, tests, or entry points. Start by locating how globals, class fields, and identifier strings are represented during compilation, then determine the affected lookup paths and define benchmarks or tests that show numeric identifiers preserve behavior and improve access.

Written by the indexing model from the issue text.