Preach it, man, preach it! I'd go further - performance matters much less than 1% of the time in my experience. Maybe 0.1% would be more accurate. Even taking an edge case like Google, the performance sensitive stuff they do can't be more than a few percent of their total effort. Their best idea - map-reduce on a gigantic cluster - seems to me to be mostly a great way to speedup slow code with no programmer effort!
It's a damn shame though - optimization is such fun. HTML::Template::JIT was a blast to write, but it's worth noting that despite being the absolute hands-down fastest templating engine available it's virtually never been used. I couldn't even justify using it in a mass-mailer with very tight performance requirements, templating just wasn't the bottleneck (MIME::Lite was).