Angular 10 - Virtual page load times increased

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We just updated our application from Angular 9 to Angular 10 last week and noticed that in our End User Monitoring data, we've seen a significant increase in all of our load times for our virtual pages (like a 5x increase on average from 3 seconds to 15+ seconds). It does not appear from an end user perspective that the page is loading any slower than it did previously, and when I look at examples of slow pages in EUM, I see large gaps in the resource waterfall where it appears nothing was going on. 

Going thru the EUM documentation, I saw that Angular 9 support was introduced back in June. I'm wondering if anyone else has seen issues after upgrading to Angular 10, and if there is any ETA on official support for Angular 10? Thanks.

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After doing some more research, I have found that our virtual pages are including time from when the last base page was loaded. So somehow each virtual page after that has the same start time, so each one gets progressively worse as it seems that somehow AppD is starting the timer from the last time a base page was loaded. So if I go to 5 virtual pages after my last base page, each one appears to have the same "start time", so each page's timings gets progressively worse. Not sure what may have caused this other than our Angular 10 upgrade which is when the issue started with our application, but I'm not sure what in that release may have caused this.

[thespacerace · Accepted solution]

After trying some different ways to resolve this, we appear to have found an EUM config setting that has resolved this issue for us.

We added the following to the adrum config code in our Angular application:

config.isZonePromise = true;

After setting this, we are no longer seeing the inaccurate virtual page load times we had been previously. It's not clear why this resolved our issue.

This setting is referenced under the 'Fetch API Support for SPA2 Monitoring' heading in this document:
https://docs.appdynamics.com/display/PRO45/SPA2+Monitoring