When system performance on Linux is affected by using too many file descriptors, usually an error can be seen in the log file '(Too many open files)'. Although this affects the entire system, it is a fairly common problem.
This mini-HowTo assumes that you’re running Debian Unstable (Sid), but it should also work if you’re using Testing or even Ubuntu. It also assumes you’re doing all these steps as root.
This blog's entry made my day: Upgrading my old Berkeley DB svn rep from 4.2 to 4.3 without any hassles. Worked as described (I used the --with-apr option).