I did some quickie benchmarks of a couple of types of page view, comparing 1.3 with 1.4 under a small variety of option variations.

See the fun: http://meta.wikimedia.org/wiki/MediaWiki_1.4_benchmarks

Since the speed benefit of a parser cache hit is so great on non-trivial pages, I've also tweaked the parser cache to work without requiring memcached. It's now enabled by default.

When running without memcached, parser cache drops will be kept in the objectcache table, where until now we've just been keeping the message cache. Zlib will be used if available to compress the size of the dumps. It's possible that on a relatively active site the objectcache garbage collection will conflict too much; if anyone notices any such problems it can be adjusted.

I've also been working on squeezing extra milliseconds out of the fixed per-page costs (initialisation, skin rendering, etc). These do add up...

-- brion vibber (brion @ pobox.com)