# How can i optimize pdf download time?

**URL:** <https://pdfjs.community/t/how-can-i-optimize-pdf-download-time/2869>\
**Category:** Technical Support\
**Tags:** pdfjs-express\
**Created:** [October 11, 2023, 8:52am UTC](https://pdfjs.community/t/how-can-i-optimize-pdf-download-time/2869 "2023-10-11T08:52:53Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![l.maglie](https://avatars.discourse-cdn.com/v4/letter/l/ce73a5/32.png) [@l.maglie](https://pdfjs.community/u/l.maglie)\
**Post date:** [October 11, 2023, 8:52am UTC](https://pdfjs.community/t/how-can-i-optimize-pdf-download-time/2869/1 "2023-10-11T08:52:53Z")

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Goodday everyone,  
i would like to have some suggestions about how can i improve the speed of Pdf.js express web viewer.  
I often have to show users pdfs that weight over 40-50 Mb that resulting in at least 15-25 seconds of waiting. i tryed to linearize the pdfs but it doesn’t seem to do much.  
Is there a way to improve the performances, am i doing something wrong?

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**Author:** ![kkim](https://avatars.discourse-cdn.com/v4/letter/k/3ab097/32.png) [@kkim](https://pdfjs.community/u/kkim)\
**Post date:** [October 11, 2023, 10:17pm UTC](https://pdfjs.community/t/how-can-i-optimize-pdf-download-time/2869/2 "2023-10-11T22:17:34Z")

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Hi there,

Thank you for contacting Pdf.js express forums,

Generally you do want to test against the demo to compare the loading speed:

> **[PDF.js Viewer Demo | PDF.js Express](https://pdfjs.express/demo)**
>
> Try the PDF.js Express Viewer demo: 26 out-of-the-box annotations, PDF form filling, e-signatures, UI customization, light/dark themes & more.

If you are experiencing a much slower load, then it could be your environment, and we would need a minimal sample project that can reproduce the issue to diagnose.

Best regards,  
Kevin Kim

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**Author:** ![l.maglie](https://avatars.discourse-cdn.com/v4/letter/l/ce73a5/32.png) [@l.maglie](https://pdfjs.community/u/l.maglie)\
**Post date:** [October 16, 2023, 1:43pm UTC](https://pdfjs.community/t/how-can-i-optimize-pdf-download-time/2869/3 "2023-10-16T13:43:09Z")

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Yes, it seems to be my project because in the demo the file is loaded almost instantaneously.  
I will try to provide you with sample code as soon as possible. In addition to the link to the example, what datas should I provide you with?  
Best regards,  
Luca

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**Author:** ![kkim](https://avatars.discourse-cdn.com/v4/letter/k/3ab097/32.png) [@kkim](https://pdfjs.community/u/kkim)\
**Post date:** [October 16, 2023, 4:38pm UTC](https://pdfjs.community/t/how-can-i-optimize-pdf-download-time/2869/4 "2023-10-16T16:38:42Z")

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Hi there,

The PDF file that you used as well as a minimal runnable sample project as either a zip file you can attach or link or a public repository would be sufficient.

Best regards,  
Kevin Kim