Troubleshooting mobile UI thread blocking and background execution timeouts?

Hello everyone,
I’ve been integrating the WebViewer into a mobile-first document management project recently and I’m really impressed with the rendering fidelity, but I’ve recently hit a persistent technical snag regarding the interface responsiveness. Whenever I have several automated background tasks running—specifically for high-frequency data extraction or custom PDF indexing scripts—the entire browser interface starts to stutter quite a bit on my phone. It feels like the main thread is blocking during the initial handshake with the server, which results in the page hanging for several seconds before the document viewer or annotation tools actually become interactive.

I’ve already verified my local hardware load and checked my worker transport configurations, but these “micro-freezes” persist during peak execution of the background processes. I even went through a clean https://deltaexector.com/blog/delta-blox-fruit-script/ setup for my mobile execution environment to see if using a more isolated script handler would stop the browser from stalling while I’m navigating the community dashboard or my project interface on my iPhone, but I’m still hitting these intermittent timeouts where the UI just stops responding in real-time. It is becoming quite frustrating to manage the document workflow effectively on the go when the management tools won’t stay fluid and the command response is so fragmented.

Has anyone else here dealt with similar execution lag or UI thread blocking specifically when running automated script managers alongside a data-heavy SDK like Apryse on a mobile browser? I’m trying to determine if this is a conflict with how modern mobile browsers are prioritizing the JavaScript execution for the WebViewer or if there is a specific optimization I should be looking at in my mobile settings to keep the handshake stable. I’d really appreciate any insights or shared experiences on how to keep the execution flow smooth so the document processing experience stays snappy!

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Hello @amandaisaac2812 ,

Thank you for posting on our forum.

If you have not already, please see our best practices guide here for information on how to best optimize WebViewer usage for performance: https://docs.apryse.com/web/guides/best-practices. You can also find our FAQ on slow-loading related issues here: https://docs.apryse.com/web/faq/slow-loading

Additionally, if you have not already we recommend configuring your application to support WebAssembly threads, as this can help parallelize work and reduce main thread blocking. See our blog here for more information: https://apryse.com/blog/how-to-enable-webassembly-threads

To help us investigate the issue further, feel free to provide additional information regarding how you’ve been able to reproduce these “micro-freezes” and intermittent timeouts. This would include the following:

  1. WebViewer constructor with all options defined
  2. Does this issue occur with particular file(s), such as larger-sized files?
  3. Have you been able to replicate the issue using some of our hosted samples? JavaScript PDF Viewer Demo & Samples
  4. Which devices / browsers have you used for testing? Please provide the exact version(s) tested.
  5. Are you using WebViewer Server? If so, what version of WebViewer Server? Are you able to reproduce the issue without WebViewer Server?
  6. SDK version number: https://docs.apryse.com/web/faq/version-number

Best Regards,
Jacob Romano Carlsen
Web Development Support Engineer
Apryse Software Inc.

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