User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/115.0

Steps to reproduce:

1. Open the attached html file
2. View source (Ctrl+U)

The attached html file is a not fully complaint html file that is also happens to be a valid bmp file.

Reproducible in 115.0b9, 114.0.2
Not reproducible in 90.0

Actual results:

• A firefox.exe process hangs at 12-13% (8 Core System).
• Source is never viewable
• Tab containing the html page is also not viewable
• If the Firefox window is closed the process continues running for about 20 seconds. A new Firefox window cannot be opened for about 20 seconds or until the process is killed via Task Manager.

Expected results:

• Process does not hang
• Source can be viewed

https://profiler.firefox.com/public/7p2ddbfpdjwqfshy0t4yvsrbe0sz546fzy133br/calltree/?globalTrackOrder=0wa&hiddenGlobalTracks=1w8&hiddenLocalTracksByPid=8188-01~14672-0~23668-01~6704-0wb&thread=q&v=9

Thanks for reporting. This looks like the same situation as bug 1838250.