FWIW - mupdf is simply not fast. I've done lots of pdf indexing apps, and mupdf is by far the slowest and least able to open valid pdfs when it came to text extraction. It also takes tons of memory.

a better speed comparison would either be multi-process pdfium (since pdfium was forked from foxit before multi-thread support, you can't thread it), multi-threaded foxit, or something like syncfusion (which is quite fast and supports multiple threads). Or even single thread pdfium vs single thread your-code.

These were always the fastest/best options. I can (and do) achieve 41k pages/sec or better on these options.

The other thing it doesn't appear you mention is whether you handle putting the words in reading order (IE how they appear on the page), or only stream order (which varies in its relation to apperance order) .

If it's only stream order, sure, that's really fast to do. But also not anywhere near as helpful as reading order, which is what other text-extraction engines do.

Looking at the code, it looks like the code to do reading order exists, but is not what is being benchmarked or used by default?

If so, this is really comparing apples and oranges.