It just depends what codec the developer used when compressing animations, old codecs like MPEG work fine without any hardware acceleration. I think few people pay attention to such things (both developers and users). That's why it's roulette - one goes well, others slow down. Only those who use the latest video chips win, they have any go fast and smoothly without using CPU.
While it definitely gives you more insight as to who the older characters are, it's not necessary to play. Masters of the Island is a follow-up, but it's a completely different story with a focus on the new characters that weren't in NSFW. If you like professional wrestling you might enjoy it, but most of the important stuff has been covered/is being covered as the boys learn about it through their dad.
