Affected versions
Nightly aarch64 68.0a1 2019-05-14
Beta aarch64 v67.0b19;
Release Candidate 67.0

Affected platforms
ARM64 - Windows 10.

Steps to reproduce

• Launch Firefox
• Go to http://www.pdf995.com/samples/pdf.pdf
• Click on the Print button
• Select any printer or print to pdf
• Click on the "Properties..." button

Expected result
The Properties windows should be displayed.

Actual Result
Firefox will become unresponsive for like 2-3 minutes. The properties window will appear only after that waiting time

Note
NOT reproducible on Windows 10 Desktops.

I filed a similar bug in the past: bug 1522911.

Does this reproduce in other apps, e.g. Notepad? (In bug 1522911, it affected all apps, which is why that one was resolved as invalid i.e. not-a-Firefox-bug.)

If this specifically affects Firefox & no other apps, then it makes sense to track this. But if all apps are affected, this should probably be duped to bug 1522911 or closed as invalid.

Yes, it does happen with notepad too. Duping it to Bug 1522911. Thanks!