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With Firefox 126.01, the new PDF Editor spawns 10 firefox program instances on Windows 11 64b.

Making moves

With Firefox 126.01, the new PDF Editor spawns 10 Firefox program instances on Windows 11 Pro 23H2 64b (as shows by the Task Manager) and cripples the computer by swamping the CPU and IO. I wonder if I am on the right chat page for submitting a bug report. If I do not browse to any PDF file, everything is fine as before. As soon as I view any PDF file in Firefox, my computer turns unusable.


Making moves

Could you file a bug: ?

In order to help us to figure out what's could be wrong, you should:

  • attach the pdf causing your issue
  • install the Firefox profiler: and take a profile while loading the pdf
  • attach your configuration from `about:support`

That said, opening Firefox 126.0.1 with only one tab spawns 9 processes and adding a tab with a pdf just spawns one process for me. In looking at `about:processes`, I don't see anything especially wrong.


Could you set Firefox not to run scripts embedded in PDFs, just in case that is the issue. Here's how you do that:

(A) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

More info on about:config: Configuration Editor for Firefox. Please keep in mind that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.

(B) In the search box in the page, type or paste pdfjs.enableScripting and pause while the list is filtered

(C) Double-click the preference (or click the toggle button at the right end of the row) to switch the value from true to false

That just leaves everything else involved in rendering a PDF...