This Matomo plugin writes all tracking requests into a Redis instance or a MySQL
queue instead of directly into the database.

This is useful if you have too many requests per second and your server cannot
handle all of them directly (eg too many connections in nginx or MySQL).
It is also useful if you experience peaks sometimes.

Those peaks can be handled much better by using this queue. Writing
a tracking request into the queue is very fast (a tracking request takes in
total a few milliseconds) compared to a regular tracking request (that takes
multiple hundreds of milliseconds). The queue makes sure to process the
tracking requests whenever possible even if it takes a while to process all
requests after there was a peak.