Memory leak when linking to MathJax directly

Issue Summary

I am using a fork of rehype-mathjax which upgrades from v3 to v4, in a project containing approximately 1,900 markdown files, the majority of which contains maths. Recently the build has been surpassing 4 GB of memory usage on my personal machine, and MathJax seems to be the culprit, as disabling it removes the memory leak.

Steps to Reproduce:

Run pnpm build on the project linked above.

I know this can hardly be considered a “minimal” reproduction, but this bug obviously requires a substantial number of files to reproduce. If there is something else you would like me to try, please let me know.

For what its worth, the rehype-mathjax fork follows the approach of linking to MathJax directly. Unfortunately my PR to remark-math has been open for 5 months with no response.

Technical details:

• MathJax/src Version: 4.1.3
• OS: 26.5.1
• Node: 24.7.0

Start by running pnpm build in the linked project with MathJax enabled, then compare memory usage with MathJax disabled. Focus on the direct-linking approach described in the MathJax server documentation and verify that processing the large markdown collection no longer grows beyond the reported 4 GB usage.