What does the term "Speed" mean in a speaker?

mass and inertia matter, but you missed one parameter, driver surface area, which determines the amount of excursion for a particular level of volume, which goes a long way determining the linearity of the response.

mostly in the mid bass you find one driver, maybe two. or two crossed over. my speakers each have -4- 97db, 7ohm, 11" ceramic matrix woofers. covering 40hz--250hz. with all that surface area and a very stiff light ceramic membrane, the need just a tiny bit of excursion so they stay linear. and the amplifier is not stressed by the load with 97db efficiency.

so you get planar or horn type speed, but dynamic cone impact. images have weight and authority. tonality is maintained and not washed out.

Speakers with better transient response are more revealing and can easily be made to sound crappy with bad or poorly set up equipment which I think is why some people have a jaundiced opinion of them particularly horns which are also not easy to design.

I am not quite sure this is entirely true.  A driver that has better transient does not mean it should have more detail or more revealing.  Better transient allows better micro-dynamic or macro-dynamic or both, BUT dynamic is not the same as detail or at least it's not a one to one exact.    

Now on the other hands, if a driver has more "resolution" then it will have more detail, but a more accurate characterization is to say the driver will "reveal" more details.  It shouldn't create more details that was not on the tape in the first place.

Transient and resolution are mutually exclusive that is one driver can have either or both.  Having one does not automatically also having the other.

Aluminum driver is usually perceived to have more "details" but a lot of that comes from it upper frequencies which tend to have a lot of break up and people sometimes interpret excess high frequencies as "detail".  And if the designer does not address the break-up, then aluminum will sound "crappy", but is it the driver fault or the designer fault?  I personally have used some cheap aluminum driver and expensive paper driver, and although the aluminum may appear to sound faster, the more expensive paper driver reveals more details, more natural detail.  So go figure.  

As for speakers that "sound crappy with bad or poorly set up", I think a lot of that comes from final implementation.  I've had the Thiel CS2.4 which is very revealing but it never sounds crappy even on bad recordings.  Speakers that sound crappy on bad recordings tend to have excessive energy on the high frequencies or some weird frequency response.  

I think there's a big gap between a speaker that sounds fast, and a driver that IS fast.

I mean, there's a lot of reasons for speakers having more detail or jump factor. The actual transient response of the drivers used does not really contribute to all of it.
How the speaker mates to the room, and frequency response I think are probably the first two things the casual listener associates with speed.

That's fine, nothing wrong with that since the end result is what matters.

I don't understand why manufacturers don't post 0-60 and 1/4 mile times?

It would make speaker selection much easier.

I don't understand why manufacturers don't post 0-60 and 1/4 mile times?

It would make speaker selection much easier.

You can't be serious.