Reduce logging overhead

In 0.3.5 release while examining #114, I noticed a large number of `clock_gettime()` and `gettimeofday()` calls, along with `connect()` to `/dev/log` for each syslog message. Additionally I found multiple open file descriptors for the same log file (one per listener) and callgrind indicated a significant portion of time was being spent in `strftime()`.