Can you please reconfirm that there is a difference between 65 and 66 on the same hardware under the same circumstances (e.g. load both immediately after startup without loading anything else)?

If there is a regression here we should definitely investigate.

This is not likely CrOS specific, just likely more apparant on slower CrOS devices.

Based on the following comment
"No delay is seen in Linux and WindowsOS"

adding the CrOS label for now.

> Can you please reconfirm that there is a difference between 65 and 66 on the same hardware under the same circumstances (e.g. load both immediately after startup without loading anything else)?

I tried Linux builds 64 vs 66 on my workstation, visiting chrome://settings/clearBrowserData and measuring the time until the dialog shows up (average of 5 runs):

Linux 64 (stable): 990ms
Linux 66 (Tip of tree): 1096ms

Also tried a Linux ChromeOS build 66 (ToT): 1600ms
Could not find an easy way to run Linux ChromeOS 64/65 locally.

So there seems to be a slow down even in non-CrOS builds, although ChromeOS seems to be more than 50% slower compared to non-CrOS builds.

(Running Linux ChromeOS on a branch should be exactly the same as running a Linux build on a branch, just add target_os = "chromeos" to args.gn.)

I'm not sure what I am expected to do for this? As we know, CrOS Settings is larger, and CrOS devices are much slower, so a small regression on a fast Linux Desktop is very likely to be much exaggerated on a CrOS device.

Perhaps we need to revisit ownership of Settings issues that have greater impact on CrOS. +abodenha@ for resource allocation consideration.

According to UMA stats, there is no significant difference in Settings load times between 64, 65, and 66, with the mean being right around 2 seconds. Hooray for metrics.
64: https://uma.googleplex.com/p/chrome/histograms?endDate=20180228&dayCount=1&histograms=Settings.LoadCompletedTime.MD&fixupData=true&showMax=true&analysis=0.25%200.5%200.75%200.95%200.99%200.995&filters=platform%2Ceq%2CC%2Csimple_version%2Ccnt%2C64.0%2Cisofficial%2Ceq%2CTrue&implicitFilters=isofficial
65: https://uma.googleplex.com/p/chrome/histograms?endDate=20180228&dayCount=1&histograms=Settings.LoadCompletedTime.MD&fixupData=true&showMax=true&analysis=0.25%200.5%200.75%200.95%200.99%200.995&filters=platform%2Ceq%2CC%2Csimple_version%2Ccnt%2C65.0%2Cisofficial%2Ceq%2CTrue&implicitFilters=isofficial
66: https://uma.googleplex.com/p/chrome/histograms?endDate=20180228&dayCount=1&histograms=Settings.LoadCompletedTime.MD&fixupData=true&showMax=true&analysis=0.25%200.5%200.75%200.95%200.99%200.995&filters=platform%2Ceq%2CC%2Csimple_version%2Ccnt%2C66.0%2Cisofficial%2Ceq%2CTrue&implicitFilters=isofficial