In my mind, this is an artifact of tone, not actual driver speed, but since panel and cones couple so differently to a room, panels are often described as fast, while cones as slow. This is not really what’s going on, but whatever. :)
Agreed, that makes sense to me.
(And resonances in a speaker can of course change perception of tone).
I have a pair of old Thiel 02 speakers which were cheap even circa early 80’s. It’s a good design making the best of a cheap box and cheap set of drivers at the time.
But boy does it sound "fast" in the usual audiophile sense of having transients pop out vividly, and having no bass overhang. They are rhythm-machines in that regard.
It’s just that they have a certain frequency balance, very flat in the bass region and maybe a tiny dip in the right places, to have a frequency response that creates this impression.
At least, from what I can infer.