Webhtml viewer file loading freezes all the clients

Good Day,
Following my previous topic ( Windows is to slow to load pdf ), I have a web app which uses a Webhtml viewer to load and show a PDF file.
When I run it on Windows, it takes a long time to load the PDF. When i run the same app on Linux or MacOs, it loads it very fast.
As a result , if I run the web app on Windows and two or more clients are connected, until the PDF file is loaded in one client, all the others “freeze” and the user cannot select or use any component.

My question is, if there is a method for the app to continue to respond to the other clients while the WebHTML viewer is loading the PDF?

Something similar to Visual Basic’s “DoEvents” method, for Web apps