Gentoo using nptl, gcc 3.4.1, kernel-2.6.7, and the newest glibc, in pure 64-bit mode (you need a nvidia card for this, ati has no 64-bit drivers) is as good as it gets. The newest gcc (3.4.1) makes a world of difference in both compile time and speed of the resulting binaries, and ntpl is damn nice for a number of apps that use it (especially java apps).