[Dovecot] POP3 Performance

[Jan-Frode Myklebust]

One quick fix to try, if it's the login-time that's killing you, is to enable
auth caching:

	http://wiki2.dovecot.org/Authentication/Caching

that should offload your backend LDAP-servers from doing bind() on ever
login, had a huge login performance impact for us. We use
"auth_cache_size = 100 M", which gives us 99% cache hits:

	dovecot: auth: Authentication cache hits 3654591/3669119 (99%)
	dovecot: auth: Authentication cache inserts: positive: 588030 80931909B, negative: 912 49888B


   -jf