> get decent performance
The issue is that in Computer Science "real-time" doesn't just mean "pretty fast", it's a very specific definition of performance[0]. Doing "real-time" computing is generally considered hard even for problems that are themselves not too challenging, and involves potentially severe consequences for missing a computational deadline.
Which leads to both confusion and a bit of frustration when sub-fields of CS throw around the term as if it just means "we don't have to wait a long time for it to render" or "you can watch it happen".