From Dynatrace UEM we can see that on some clients machines
sometimes the browsers do not render a page fast enough.
For example, in 3% cases one specific page (Notifications)
are shown in 10 seconds instead of less than 1 second.
We know that this delay is not related to servers or
network, APM clearly indicates that this slowness is related to a JS or
internal browser logic on clients machine.
Are there a way to look “inside” of web browser processes to
identify the cause of the slowness?
I would try to find a correlation between these slow visits. Things I would check for include: browser type, browser version, IP address, geographic location, OS, client error count, date and time, etc. If for instance you determine they're all coming from a specific browser version you could download that browser and investigate it further from there.
Hope this helps,