Micro does not respnoe when edit specific file

Description of the problem or steps to reproduce

Open it with micro and try to edit. It won't respond anymore and killing terminal doesn't kill micro

tileset_env_test

Specifications

Commit hash: 2d82362
OS: Debian12
Terminal: foot,

[JoeKar]

Duplicate of #2839

There is still an recursion within highlightEmptyRegion() and highlightRegion() due to the "fix" of nested highlights.
The same can be reproduced e.g. by using the "NewTab" page of Firefox or some other nested HTML or XML likes where the whole nesting takes place on one line.

This definitely needs a fix to remove this nasty recursion and to improve the performance.

[JoeKar]

As written in #2839 am at this topic and use your file as benchmark too, but the rework takes a lot of time. The easy and low cost improvement reduced the parsing time by the half.