I installed the 3.8.2 version for our Moodle.
It has been tested on Development and Preproduction servers and I did not notice any performance issue.
On the other hand, in production we have a different infrastructure consisting of a Galera cluster with 3 nodes and the Moodle is very slow (see in attachment the results of our benchmark plugin).
I don't manage the configuration of the Galera cluster, but I could ask the dedicated team for more information if you think that there are adjustments to be made on their side.
In the meantime, digging through the Moodle forums, I have configured the cache (see attached screenshot for data warehouses) and below:
APCu cache for:
Accumulated information about modules and sections for each course
HTML Purifier - cleaned content
Language string cache
List of available languages
Activity completion status
Course categories tree
Course group information
Database meta information
Grade items cached for evaluating conditional availability
Plugin info manager
Plugins available callbacks
System capabilities list
This stores the list of event subscriptions for individual courses
User grades cached for evaluating conditional availability
YUI Module definitions
For the rest it is either "Default static store for request caches" or "Default file store for application caches" or "Default session store for session caches".
Does this configuration seem correct to you?
Thank you in advance for your advice and help.
No. Moodle sees a very slow file system behind its $CFG->dataroot, what we just call "moodledata". The Moodle Bench reports:
3 Reading file performance
(Read a file multiple times to check the reading speed of the Moodle temporary folder)
current 0.567 acceptable. 0.5
4 Writing file performance
(Write a file multiple times to check the writing speed of the Moodle temporary folder)
current 5.6 acceptable 1.0
Notice that the numbers are in seconds - smaller numbers are better.They have to be clearly better than the acceptable limits. Specially the write speed, completely unusable.
What was the Moodle Bench score? It is left out in your screen-shot.