Resolve iOS PDF Freeze Bug

I manage the online PDF editor at https://formsigny.com/new/pdfj/. Everything works smoothly on desktop, but on iOS browsers (Safari, Chrome, WebView) the interface locks up after roughly ten minutes of active editing. Typical reproduction steps are:

1. Upload any PDF from an iPhone or iPad.
2. Add a photo, signature, and a few text boxes.
3. Continue editing for about 10 minutes—eventually the entire page freezes and becomes unresponsive.

I need someone who can replicate this behaviour, trace the root cause, and implement a permanent fix.

What I expect from you
• Deep-dive analysis of the front-end stack (pdf.js / JavaScript / WebKit) to pinpoint the exact memory leak, event-loop blockage, or rendering issue that appears only on iOS.
• Clear technical explanation of the defect, supported by console logs or Web Inspector screenshots.
• Code-level remediation plus any configuration tweaks, followed by deployment on my staging server.
• Regression testing to confirm:
– The editor remains responsive on iOS for at least 30 minutes of heavy use.
– All main features (add photo, add signature, add text) still work flawlessly on desktop browsers.
• Concise documentation of changes and profiling steps for future reference.

You’ll get full Git repo access, staging credentials, and test PDFs. If you have solved similar WebKit-specific freezing or memory issues before, highlight that experience in your bid. I’m ready to start as soon as the right expert is found.