Large PDF takes several minutes and GB to render

[Jap2-0]

I don't know how focused you are on performance, particularly in such extreme cases, at the moment, but I thought I'd file this in case it might be of help at some point.

Attach (recommended) or Link to PDF file here:
https://www.dot.state.mn.us/d7/projects/14newulmtonmankato/pdfs/projectlayoutmarch2021.pdf

Configuration:

• Web browser and its version: Firefox Nightly 106
• Operating system and its version: Windows 10 21H1
• PDF.js version: 2.16.71
• Is a browser extension: No

Steps to reproduce the problem:

1. Open linked PDF (~35MB)
2. Wait

Acrobat loads this in about 20 seconds, whereas pdf.js takes about 4.5 minutes. Interestingly, Acrobat does not keep the whole page renders but instead re-renders as you scroll, while pdf.js renders the entire page (eventually) and keeps it saved. Acrobat uses about 650MB of memory, while pdf.js uses about 3GB (evenutally falling to about 700MB after some amount of time - perhaps switching to another tab? - but also several hundred MB in the GPU process (although that number is far less consistent for me).

I can try to get a profile if that's helpful; a full profile is too large for Firefox to process, but if partial ones are useful I can work on that.

[Snuffleupagus]

This only (reasonable) way to fix this would be to implement #6419, of which this is thus for all intents and purposes a duplicate.