So if anyone tries telling you that optimizations are irrelevent because of processor speed,
Did you hear EpicBoy say that? The fastest methods of doing things usually stop being the fastest with new technology. Things like lookup tables save infinitisimal amounts of time on older CPUs, and are *SLOWER* on new CPUs.
You would be much better off looking at why your game has to call Sin/Cos millions of times a second rather than speeding up the calls themselves, ie optomising your algorithm rather than its implementation.
And Sin/Cos lookup tables isn't the only thing that is out of date anymore, far from it, it is just a classic example.