There are a few things going on here.
First, Windows I/O is not the fastest, which is especially problematic with the ViewRenderer, as quite a number of files are loaded by it.
Second, there’s a bottleneck in the PluginLoader which we’re addressing now (and you can test with the 1.7.0 preview release now available, or using svn trunk); in tests on *nix machines under load, we saw a 12.5% performance gain.
Third, you should be using an opcode cache; this will significantly speed up the application regardless of version.
