in 1993, on x86, writing in asm is definitely a bit baffling, but not entirely out of the norm, especially if you want to support 8086/8088 class hardware (earlier pc-98 machines)
but if you're targeting a 386 or better, you might as well write in C （⌒∇⌒ゞ）
and even if you're targeting a 286, you could (eg, wolf3d)

one thing to note: sonic spinball was made in like 3 months (seriously), they genuinely didn't have any time to optimize anything
it's also way slower hardware (a 7Mhz 68000), but a lot of the issue was just that they didn't bother making it run well, they needed it done fast