What does 'Fast mean?

Porziob ... it's pretty easy to design a speaker cable with enough inductance to roll off higher frequencies. Too much capacitance and a wide bandwidth amp might start to oscillate.

Similarly it's pretty easy to design an interconnect with enough capacitance (usually the shielding) to cause rolloff where the source has a marginally high output impedance and the amplifier a marginally low input impedance. Not enough shielding and RFI becomes a problem.

The ability of an amplifier to control the speaker to deliver dynamic transients with little ringing or overhang is certainly not something all amps share ... hence the difference in sound.

It's not quite so simple as you imply.

You can listen to more music in less time.

my girl friend says im fast maybe i need to learn how to oscillate..funny about thats why amps are heavey phd

I take "fast" to mean how quick the output of a device can follow a change at the input - which would pretty much describe the above impressions of transients, attack, etc. As for cables, well... they either do the job or they don't. Poorly designed cables will result in modifiers such as "bright" or "bloated" while the good ones are hardly distinguishable unless you really move up the food chain in equipment. All this IMHO, as I have not heard all or every possible combination of gear.