In preview mode typing text in editor is slow and delay

Using markdown-it: https://www.npmjs.com/package/markdown-it
- Katex render: https://www.npmjs.com/package/katex
```js
previewRender: (plainText, preview) => { // Async method
setTimeout(() => {
preview.innerHTML = md.render(plainText);
}, 250);
},
```
If content include many math formulas in preview mode typing text in editor is slow and delay.
[screen-capture.webm](https://user-images.githubusercontent.com/45259239/189586245-d77cc495-0994-4efd-945f-a34690ff6cdb.webm)
Full content in: https://viblo.asia/p/lam-gi-khi-mo-hinh-hoc-may-thieu-du-lieu-co-nhan-phan-2-semi-supervised-learning-vyDZOREkKwj
**Version information**
- OS: [Linux - Ubuntu]
- Browser: [Chrome Version 98.0.4758.102 (Official Build) (64-bit)]
- EasyMDE version: [^2.16.1]

Start with the previewRender callback shown in the report, using the linked full content to reproduce typing lag with many math formulas in preview mode. Done means typing no longer has the reported delay while the preview still renders correctly; the issue names no repository files or tests, so locating the implementation and regression coverage is part of the work.

Written by the indexing model from the issue text.