Server performance

Some ways to evaluate server performance and to figure out what's wrong:

tail -f access.log

This really helps to get a real-time impression of requests made on the server - E.g., to see how much of the traffic is from bots:

sudo tail -f /var/log/apache2/access.log

free -h

Use free -h to check for available memory. E.g.:

$ free -h

Memory usage:
              total        used        free      shared  buff/cache   available
Mem:           47Gi        24Gi       591Mi       118Mi        21Gi        21Gi
Swap:         8.0Gi       399Mi       7.6Gi

Only 591Mi out of 47Gi is free, or 1.26%. That sounds problematic, probably leading to MySQL connection errors.