That's a reasonable definition. It also pushes things closer to what we think we can do now, since the same logic makes a slower AGI equal to a person, and a cluster of them on a single issue better than one. The G (general) is the key part that changes things, no matter the speed, and we're not there. LLMs are general in many ways, but lack the I to spark anything from it, they just simulate it by doing exactly what your point is, being much faster at finding the best matches in a response in data training and appearing sometimes to have reasoned it out.

ASI is a definition only in scale. We as humans can't have any idea what an ASI would be like other than far superior than a human for whatever reasons. If it's only speed, that's enough. It certain could become more than just faster though, and that added with speed... naysayers better hope they are right about the impossibilities, but how can they know for sure on something we wouldn't be able to grasp if it existed?