Apache – How to Monitor Current Requests

ps aux | egrep '(apache|httpd)' typically will show what apache is running as.

Usually you do not need to change the default user, "nobody" or "apache" are typically fine users. As long as its not "root" ;)

edit: more accurate command for catching apache binaries too

In addition to your test script try also running a benchmark application like ApacheBench (ab) or Siege. Also run this and your test script on the local server itself. If it is a router/network issue your tests on the local server should show no issue. You can play with the concurrency request of ab/siege to see if the issue happens more at a higher concurrency. Test it with a variety of files and types of files to see if that makes any difference.

The key to most troubleshooting is replicating the issue and then narrowing down the cause. Since you describe it as "random" I would try and focus on attempting to replicate the issue as reliably as possible. If you cannot replicate the issue then you won't truly know if you actually solve it or not in the end.

It may be in fact the case that "no-one on the internet has experienced this issue". There are virtually an infinite number of hardware/software/application configurations that make diagnosing some issues like this difficult. People also may use a different description for the same problem: what you call "random Apache lag" someone else may call a "remote Ethernet performance issue".