Fotorama product picture script is extremely slow on mobile devices

[andidhouse]

1. Magento 2.1 via download / nginx / php7 / redis / varnish / mariadb

Steps to reproduce

1. Go to a product page with a smartphone (even if no product picture is uploaded and the default backup picture is there)
2. look at the load time of the product page

Expected result

1. The product site loads very quick on smartphones and tablets too

Actual result

1. The fotorama script is extremely slow on smartphones and causes the whole product site to load several seconds without showing a picture.
   You will realize that that all parts of the product page load extreme fast but not the fotorama picture script.
   Also if there is no picture uploaded and the default backup picture is loaded (with just a view kbs) the script needs seconds to render the default backup picture with just a view kbs.

I think this is not exactable on mobile devices at all. There are other ways to load the product pictures first before calling a complex script which blocks the load of the first picture and just shows a spinner for several seconds.

[andidhouse]

We also checked this on multi servers and installations - it is not the server power or anything else.
It is the fotorama script or the implementation of it.

You can for example check out this magento2 site and you will see that the product sites need several seconds to load the pictures on mobile devices:

https://www.ninewest.co.uk

[LucScu]

@piotrekkaminski How could you move huge bugs (it's incredible that you release a so slower carousel builder for mobile) to "Feature Requests and Improvements"?
How could a user waits 5 seconds before see product's image? And in the meantime see the ugliest loader ever?

[choukalos]

Reopening; changing to bug. Internal ticket - MAGETWO-58628

Hi @andidhouse & @LucScu ; sorry our script that runs under Piotr's name auto-moved this. Looks like it was incorrectly tagged with the label improvement.

I did notice that JS on the site hasn't been bundled & minified. That should help performance some.

[piotrekkaminski]

@LucScu we have automated process that moves every ticket markes as improvement or feature request to forums. I agree this should be fixed so we have reopened it. Thanks!

[LucScu]

@choukalos On my env all js and css are bundled & minified, but product's pages are very bad user experience due to slowness of fotorama js.
Are you agree?
Do you have a fix to correct it or we have to install a 3rd part extension?

[andidhouse]

@choukalos The bundling and minify is another topic here. As far as i know this does not work correctly and is reported several times here.

As @LucScu states here - also if we bundle and minify js and css this has no huge effect. The loading time of the script is simply inacceptable for a mobile or tablet user.

[ignaciomella]

I cannot stand this. Product images loads too slow.

There's a temporary solution posted in StackExchange

http://magento.stackexchange.com/questions/134834/how-can-we-load-product-image-gallery-instantly-without-the-delay-in-magento

From what I read there, this problem lies with Magento's implemenation of the fotorama script.