Checkout page very large and quite slow.

[pynej]

Using a single store on 2.6 in production mode. No combined JS/css, with setup:di:compile, varnish, and SSL for checkout.

Normal pages work quickly through varnish as expected in 2s/100ms uncached/cached and around 12k each.
Customer pages like past orders come in without varnish as expected in 1.5-2.5s at around 40k.
Going to the checkout with a single item in my cart take 4.5s and weights in at 800k and seams to go up in size and response time.

Note that these times are for the roundtrip for the html file, not any resources or images.

[ishakhsuvarov]

@pynej Thank you for reporting this issue. We already have an internal backlog item MAGETWO-40101 to improve checkout loading time and make the page cacheable. We will update this ticket when it's implemented.

[daniel-ifrim]

@pynej @ishakhsuvarov Checkout page has in it JSON data for all payment methods and shipping methods that are disabled in admin. This is why the page html source is this large. Magento_Ui should filter out at least disabled payment methods and shipping methods.
And all regions from database are redundant in those JSON objects.

[SchumacherFM]

We ran into the same issue that all payment methods will be loaded regardless if deactivated.

Would be nice if you guys can fix it ASAP ...

[pynej]

On 2.1 We were able to enable the Merge Css, Merge JS, and Bundle Js options and with all three on the issues seam to goo away.

[SchumacherFM]

The bug is still not fixed and enable bundling and merging hides only the problem.

Customers are already complaining about the bloated checkout page.

[pynej]

Yes. I would say this is a critical issue and makes us look very bad to our customers. The site, products, and custom loggin pages are all quite fast @.5ms for cached requests and 1s for uncached requests. But anyone getting to the checkout page is in for a nice 10s delay and gets very irritated. We have even disabled some unused of the shipping modules per advice I found but that had a very minimal impact on the performance.

To clarify the checkout page is 50 times larger then any other page on the site and its loading 5 times as much javascript code. Or with bundling turned off its loading 50-90 separate scripts per page load.

Also the way that the varnish/caching works the /checkout and its resources don't benefit at all form these systems. This means that the checkout page spends 1.85s processing in PHP with all the setup:di:compile complications, all caches enabled, and opcach set up. It then has to spend a further 1.5s downloading the large file. Then it gets to loading wither 90+ scripts or the 3.5MB bundles file either way taking another 6s.

[pynej]

These example numbers are with the following disabled:
List of disabled modules:
Magento_Dhl
Magento_Fedex
Magento_Authorizenet
Magento_Paypal
Magento_Braintree

We did load a custom module for CC processing: MD_Cybersource

[pynej]

The script block stertign with this is 440KB of JSON data.

<script type="text/x-magento-init">
        {
            "#checkout": {

Most of the data here looks like it is Locality info. Region/State info that is filled in the dropdown when country is changes. At the very leas this should be changed to be loaded when the country is actually changed as 99% of this data isn't going to be used on a individual page. An api that returns the regions for the selected country will significantly reduce this page size.