Remove unneeded region definitions from the /checkout page.

[pynej]

Preconditions

1. Magento 2.1.1
2. PHP 5.6
3. Apache

Steps to reproduce

1. In admin go to Store > Configuration > General > Allowed Countries change this list to some limited set. (We selected only United States for example.)
2. Clear all Magento caches.
3. Go to the Checkout page

Expected result

1. Template/JSON code embedded in page should not have region_id definitions for all the disabled regions.

Actual result

1. There is still 320KB of region definitions loaded on every /checkout request for all the regions we have disabled. This is a major killer of performance on the checkout page as it has to download this data every time, wont be cached, and all the non-us region data in this case will never be used as we configured the site to only allow the us region.

[SerhiyShkolyarenko]

@pynej thank you for reporting! We created internal issue MAGETWO-59796, but additional investigation is necessary if the fix could be backward compatible.

[pynej]

As an aside, we were sort of able to work around this issue by correctly configuring gzip compression on php files served under SSL. This is really a workaround as the file is still large and the data still hd to be decompressed and processed unnecessarily.

[adragus-inviqa]

Maybe related to this "feature request" - #4217 ?

It was moved to the forums, as I clearly wasn't serious about the problem. The trollface didn't help my cause. I think they'll move yours to the forums, too, @pynej. Clearly not a bug.

[SerhiyShkolyarenko]

MAGETWO-40098 implies another approach and more changes, so it's a story in terms of scrum.

[SerhiyShkolyarenko]

We are closing the issue as MAGETWO-59685 fix is delivered to the develop branch. Thank you!

[magento-team]

Internal ticket to track issue progress: MAGETWO-67725