Don't talk to me about "premature" optimization until you've changed your DRAM timings to synchronize better with a graphics loop.
On racing the beam: "...changing the system default DRAM refresh from its default interval of 18 to 19, to get the DRAM refresh periods to line up with CRTC accesses."
On their full-bitrate MOD player for the PC speaker: "Each sample must take exactly 288 cycles to calculate and output or else the sound goes completely pants. This was very difficult to achieve. 4.77 MHz / 288 = 16572 Hz sample output."
I'm also amused by producing 1024-colour mode on the 4-colour CGA adapter.