Could you please provide any such Website where this happens. I am seeing Waiting for 'www.facebook.com' when the page is being loaded. 

sorry, is this a automated response?
this is a feature request.

Thank you for providing more feedback. Adding requester "ajha@chromium.org" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

useful for seeing, how extensions like ublock and Adblock when intercepting http request how it impacts (slows down) the browsing experience.

also in general a good features so users know what are the installed extensions doing, transparency..

this message can be shown when the extension is intercepting I/O (HTTP) or doing I/O (Storage, sync etc.).

Chrome doesn't wait for extensions normally. The extensions with persistent background pages that intercept network requests are loaded during the startup of the browser and this is the only case when the browser might need to wait. Also, normally uBlock speeds up loading of pages enormously, e.g. 1 second instead of 5 seconds, which I've witnessed many times over the years I've been using it. 

You need to present your case by specifying the exact steps needed to reproduce the issue in a pristine new browser profile. 

Seems this is a feature request,marking it as Untriaged to get more inputs from dev .
Thanks..!!

We actually already do this for webRequest.  [1]  You can see this if you have a *really* slow webRequest extension.  Showing this for every extension action isn't something we'll want to do, since most of them are non-blocking.  The other possible place this could make sense is if an extension has a very slow content script running at document_start, which would effectively block page load.

Given we already do this in the most egregious case (webRequest), I don't think this is very high priority at the moment.

Updating labels and description accordingly.

[1] https://chromium.googlesource.com/chromium/src/+/4314fd9c8498473c5e53a529e11d2678bd1a1ea2/extensions/browser/api/web_request/web_request_api.cc#1112

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot