I have 2 systems where in the first (route optimization platform), 1 user would, as part of just a normal 10 minute session:
- read ~100MB from the database - utilize 100% of 32-core machine CPU (and 64GB of RAM) - resulting in thousands of writes to the database - and side-effect processing (analytics, webhooks etc)
Over a course of a day, it would likely be ~10x for that single user.
In the other system - appointment scheduling - 1 user would, in 1 day, read ~1MB of data from the database, and make 2-3 writes from a single action, with maybe 1 email triggered.
I.e. load and show stuff from databases (but nothing compute intensive).
Insert / update performance is quite another story: https://stackoverflow.com/a/48480012 Even in WAL mode, one should remember to use BEGIN CONCURRENT and be ready to handle rollbacks and retries.