Add remove git tags.

Create a tag

git tag <TAGNAME>

Push tag

git push origin <TAGNAME>

git push --tags

Pull tags

git tag -l

git checkout tags/<TAGNAME>

Yml vs Json

A make a small test to test YAML vs PHP performance. The result is:

Drupal 8 shiped with a powerfull cache API able to set cache according to a context. correct usage of this cache improve the site preformence greatly.

https://www.drupal.org/docs/8/api/cache-api/cache-contexts
https://www.drupal.org/node/2451661

Memcache is caching server allow you to incrise and have great performence on your site. Drupal and memcached work very well and here the full tutorial you need to install and setup memcache server and your drupal instance.

Check module exist

if (\Drupal::moduleHandler()->moduleExists('my_module')) {

    $message = 'Module exist.';

}

else {

    $message = 'Not exists.';

}