I was able to reproduce the lag and it is prominent on Windows-10 and Windows-7 on the latest stable(50.0.2611.102) and the latest canary(52.0.2734.0).

Below is the test result as observed on diff. chrome versions and OS platform.

50.0.2661.102/52.0.2734.0 Windows 10          ~28s
50.0.2661.102             Windows-7           ~16s 
52.0.2734.0               Linux Ubuntu 14.04  ~17 s 
52.0.2734.0               Mac OS 10.11.4      ~11s

As per the bisect result from the group discussion:
Changelog:
=========
https://chromium.googlesource.com/chromium/src/+log/20f3b2d0ee459ed4d743ce9cd8c95417d74f6d04..fa7fc32c5940dfd3d734ed3231b1295da4c3303e?pretty=fuller

Good revision: 361463 
 Bad revision: 361474

As per the above revisions, corresponding good/bad chrome version:

Good build: 49.0.2573.0 (Testing showed it took ~10 s to load)
 Bad build: 49.0.2574.0 (Testing showed it took ~24 s to load)

The above changelog looks correct, hence from the above change log suspected change: https://codereview.chromium.org/1474673003

eae@: Could you please take a look at this issue.

Thank you!

Reopening this bug, as  bug 591793  comment 40 says it's not actually resolved

With Canary 53.0.2761.2 I'm still seeing much longer load times.  I did 5 trials so far in the previously mentioned Canary version, Firefox 47, and Chromium 361463 with the following results:
Canary 53.0.2761.2
Trial 1: ~43 seconds
Trial 2: ~25 seconds
Trial 3: ~23 seconds
Trial 4: ~40 seconds
Trial 5: ~23 seconds
Firefox 47.0
Trial 1: ~7 seconds
Trial 2: ~7 seconds
Trial 3: ~6 seconds
Trial 4: ~8 seconds
Trial 5: ~7 seconds
Chromium 361463:
Trial 1: ~9 seconds
Trial 2: ~6 seconds
Trial 3: ~5 seconds
Trial 4: ~7 seconds
Trial 5: ~6 seconds

In this case, I consider a trial to be from the time I click the login button/hit enter until I can open the menu and select an option and see the submenu.

Moving this nonessential bug to the next milestone.

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

Is there a timeline on when this bug will be resolved.  It is causing an issue for a large number of our end users and forcing them to use alternative browsers.

I can't see the page mentioned in step 1, can't reach the site.

Is there an reproducing page or HTML files?

A switch went down over the weekend, removing outside access to the page.  It should be available again.

Thanks, but it doesn't reproduce for me. It takes ~10 secs to load on Canary 53.0.2773.0, while Firefox nightly loads in 7secs. Any idea what I missed?

Though I can't reproduce, if the page users a lot of <option> tag, this may be  issue 620142 ?

We finally managed to make a reduced functionality page which highlights the issue we're having.  It seems to be related to the page processing extremely long JSON strings.  Demo of issue available here: https://efptest.sungardk12demo.com/gas2.50-4js/wa/r/longjson