Today I dedicated some time to hunt down my "the logins via CAS on apache2 are awfully slow, but not always, just most of the time" problem. At first I thought I had some weird network/dns/whatever issues, but after proper investigation it turned out to be that /dev/random is being used for generating the CAS cookies and my entropy pool is depleted most of the time..badaboom..APR is blocking.
This machine is a virtual server so no way I can use any Hardware RNG or anything along those lines. Given that it only runs in an internal corporate network, I've started feeding the cryptographically-strong entropy pool with rng-tools and /dev/urandom. In /etc/default/rng-tools:
Finally, no more login times issues
ps. APR 1.3.0 has switched to urandom for apr_generate_random_bytes, so in the future this won't be needed