What's the background info on this?
SCV4 is a high intensity and very well optimized game that requires very precise movements, it has various 1 or 2 frame strategies that if failed could mean the end of a run like the spike jump in 9-2, where instead of waiting all the platforms falling from the sky you just jump from the first set on the very edge hoping you don't fall to your death (missed on this run because Paul couldn't get out of the stairs in time), or the moving chandelier jump in 6-1 where like before you jump on the very edge to skip a swinging cycle of the chandelier.
Other noticeable parts of the run are the "vegas bridge" at the end of 8-2 called like that because rng determines what pieces of said bridge disappear under your feet, and a wall clip in 1-2 where swinging with your whip lets you skip a bone pillar and a set of stairs by clipping through a wall.
Even doing all of the above correctly doesn't guarantee a great run as some bosses play a big part of the final time, again to beat them fast it's a mix of good rng and skills, examples of these are the Mummy which is ideally killed in 1 cycle, Slogra (the bird with spear in B-3) and at the end Dracula which is ideally beaten in 6 cycles.
The last noticeable time improvement was last year where FuriousPaul broke the sub 32 minutes wall, other runners of this game active at this moment in time are JoeDamillio and an impressive Twocat which in less than 2 months managed to get a very low 32 minutes time.