A great old-timey game-programming hack (2013)

In the 1980s, a college student's friend had created an impressive arcade-style side-scroller game for a PC but faced a critical performance problem—the game was too slow and choppy to be playable. The programmer had already exhausted conventional optimization techniques like loop unrolling and eliminating unnecessary draws, so the author was called in to find a "crazy fix" involving the primitive graphics hardware that required manually drawing pixels byte-by-byte to the screen.