I have just been looking for new speakers. In many ways some of the most expensive speakers I listened to have not lived up to my expectations or headphones (Shure 1540; Senn 700) with dedicated amplifiers.
I couldn't figure out what is the elusive factor. I think I now have it. In my mind, the speed at which the drivers can change speed and direction seems to be the key. I think the tiny drivers in headphones are just quicker. As the drivers get bigger, there is more momentum, therefore decreased agility or what I am calling speed.
In my price range, the quickest and most appealing at this point seem to be the Vivid 1.5. Everyone prioritizes different things. These speakers certainly won't shake the room, but they seem to have what I am looking for.
Just thought I would throw out my thoughts on this night when no one is moving with much speed after all the turkey, stuffing and pumpkin pie.
Happy Holidays

Hey Crwindy,

I put the perception of "speed" on a continuum. It's always good to compare to actual music, as sometimes this speed is just not something I hear in real life, or a good pair of headphones.

The place where most speakers loose traction is in the bass, covered here ad infinitum. This is a function of the room, speakers, treatment and EQ, if any. Fix this and much else will fall into place. If you can't fix it, at least get speakers which avoid the problem entirely.

Here's something else to add: I find the concept of speed and transparency are not really the same.  The fastest sounding speakers / configurations do not also sound transparent. Color me weird.

You are correct. Perhaps what I am noticing is the lack of room interaction. Quick question. Do different speakers have different amounts of room interaction?
Thanks for your help.
Crwindy Iam big on speaker speed , transient is the one I noticed, when the speed is missing in action, speakers that have are omega rs8 super cone, super 3i Omega , and my Tekton impact monitor and the technic monitor....speed adds toe tapping if your system is musical....
Different speakers will have different room interactions because of different frequency responses and dispersion patterns. Bass is the hardest to control and tame, so, if you have a small room, for instance, speakers that don’t produce massive bass would help reduce the problem of bass reverberation.
I think a significant factor is most speakers have ported bass which introduces that column of vibrating air that is not under direct control of the driver.  Sealed box designs sound faster to me.  Their transient response in the bass is faster.  
A transmission line speaker can also offer faster speed than a ported speaker. 
Then of course there are the ESL speakers that are certainly fast but won't create any low bass unless they are huge.
Of course there are good and bad examples of all types.  However the fact remains that a sealed box bass alignment offers superior transient response to a ported enclosure.
So, check to see if all the speakers you have auditioned are ported designs.  Then see if you can find something that is sealed.  Magico comes to mind and I am sure there are a few others that might be hard to find.
Btw, I own both types and enjoy both but for different reasons.
Room interaction can depend on whether or not there are ports and where they are.  Port location can definitely make a difference in how a speaker interacts with the room.  This can give better bass support but can also excite room resonances more than a sealed box or one with a passive radiator. 

Room interaction in the bass is, in my experience, more even when the speaker has a down-firing port or ports firing both forward and backward.  Passive radiators don't seem to have as much tendency to excite the room as ports do but I'm not sure if that's really true.  The tradeoff is that the bass is less well-defined with multiple or down-firing ports.  It's not troubling but it's also not great.  The best bass is from sealed boxes when your system is in a large room in a house that has fairly lightweight construction.  That way a lot of the bass will escape through the walls and you won't get the huge variations due to resonances.  

In my opinion it's also important to have a small midrange driver.  It makes  the dispersion more even so the off-axis response in the upper midrange isn't beaming as much as it is with a large midrange.  That makes speakers much less sensitive to the room.  The room can still be too reflective but the reflections will sound pretty much like the direct on-axis sound so the overall balance doesn't get thrown all out of whack like it does when speakers have a large midrange.
for speed it is important to use Quads or Maggies; eschew cones
Like everything in audio there are always tradeoffs that need to be made. I have three systems each with speakers with a different design; Martin Logan ESL, Vandersteen 2Ci, and a home made pair of back-loaded horns with full range drivers. The single drivers are the most transparent and fastest but only with certain music and at low to medium listening levels. The 2Cis are the slowest and least transparent as compared to others but they sound great with most music, maybe with the exception of large orchestral symphonies, and can be played loud. The ESLs are the best compromise for all aspects. Of course they are all in different rooms with different size and shape and driven with different gear so the comparisons are not technically accurate but the overall perception still remains relatively close. I suspect there are speakers out there that meet all the criteria but I probably will not be able to afford them.

I think the Vivids would be a great choice. 
Re op:

It's usually tied to the phase coherence of the crossover in the midbass.