Magento 2 goes terribly slow (Developer mode)

2018 Update, Magento 2.2.4

Vagrant + Windows + Magento2 = disaster. Vagrant + Apple + Magento2 = disaster.

Ubuntu + Magento2 = cooking on gas.

Simple modules, e.g. a widget, take many days more than the expected 2-3 hours and it is not possible to remember what you are doing if it takes a minute to open a page, particularly so if you have to clear caches, compile, upgrade or anything else that should take no-time-at-all.

This I have experienced first hand, from working in an office where the options are Mac or Windows. After spending a whole day trying to change the template directive and failing to make one configuration change in 8 hours, I thought about giving it a go on a linux box to see if I had gone mad or if this Vagrant contrivance is as helpful as that drunken bum sleeping rough in the park down the road.

The aged linux box with anaemic RAM, an old SSD, stock Apache and no fancy cache things completed the task without problem, I was able to switch between developer and production modes effortlessly and get what had taken me days to not do done in minutes.

The work machine was 8th generation i7, the Vagrant setup was very much someone's baby and a lot of time had been spent building the beast. Yet tectonic plates move faster. Vagrant and virtualisation might be fashionable but it is no use for M2 development. In fact I installed M2 and did all the db and vhost setup for it in less time than it takes for a Vagrant box to build.

As for performance, since M2 on a basic linux setup is 10x faster than some clumsy Vagrant effort, it is easy to see where the real speed problems of Magento 2 are. If you fire up Lighthouse in Chrome you will see TTFB is absolutely fine but the performance halves if you minify and merge the JS + CSS. This is because M2 has a megabyte of scripts to download. This is the performance killer. If you are working on a Vagrant box then you will never see this and not have the speed to fix it. By fix it I mean write a proper theme that doesn't have nonsense such as jQuery loading on every page.

For production you need something that scales so you can get the normal speed enhancements going for that, e.g. Redis, opcode caching, Varnish, tweaked php-fpm, tweaked MySQL/MariaDB. If you are developing on Linux then you can test these things on localhost knowing they will work fine on production. With that abomination that is Vagrant you will be dabbling with these optimisations prematurely because you are hoping and praying for a performant machine because you need to get work done. However, in so doing, and with the absence of native speed, you will not get anything done.

If you don't have a spare machine to put linux on then just go to the local tip, get any PC, shove an SSD in it and you are good to go.

This is my recipe for developing themes/modules in localhost for Magento 2.2 and 2.3:

• MacBook Pro
• Valet Plus (Nginx, MySQL 5.7, PHP7.1 and 7.2 - you can easily switch between PHP versions with valet use 7.1 or valet use 7.2) https://github.com/weprovide/valet-plus
• memory_limit set to 4G
• Be sure Magento is set to developer mode: php bin/magento deploy:mode:set developer
• ALL CACHES ENABLED except FPC. Whenever I need to test a change involving config files, etc I manually delete the content of the var/cache folder or the generated/code folder for DI changes. The cache type that specially slows down everything is the Configuration cache, so it must be enabled or the frontend/backend pages will load painfully slow.
• I use Grunt Watch and the Livereload Chrome extension to see my changes to .less files without having to deploy static files with every change. https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/css-topics/css_debug.html
• Whenever I change a JS file I navigate to pub/static/[adminhtml/frontend]/[theme]/[locale]/ and delete ONLY the folder where the static file corresponding to the JS file I changed lives in. This prevents me from having to deploy ALL the static files. Magento will regenerate just the static files for the deleted folder saving a LOT of time (be sure to do a hard refresh in your browser every time you delete a static file)

It’s still not a perfect setup but it’s the fastest way I’ve found so far to be productive without pulling my hair out.