What does 'Fast mean?

Seandtaylor99, I agree with everything but the last clause of your final sentence. Accurate reproduction as you describe it does not, in and of itself, render sound fatiguing. What it does do is expose sonic artifacts that would be "rounded off" by slower gear. If an entire system is fast and accurate, this usually exposes the sonic shortcomings of the recording engineering, which is where a lot of the nasties start out. Whether it is worth paying the price of reducing overall transparency to mask some of these irritants is a question worth debating.

What reading glasses can do to make things clear.As we get old we get "used" to the way things are.Reading glasses clear things up again "quickly"...giving us that wow!!!. Getting used to a sound "your sound" then all of the sudden there is a change ,....because change was made.If it was a good change,for the better ,it probably cleared things up a bit....WOW.So it sounds fast again.

Glider, the reason for my final sentence is because I believe some audio gear overemphasises attack to make demos more exciting and sell more. More accurate does not necessarily mean more attack.

There is also definitely some gear that lessens attack and softens everything .... some will prefer this presentation.

I've always thought of "fast" as referring to the back end of the waveform. It doesn't have any overhang or ringing. The initial transient is handled pretty well by most components, but only a few components can stop as quickly as they start. In electronics it's probably a factor of the power supply and with speakers the crossover and mass of the driver. If a component distorts the leading transient signal it can make for a faster overall presentation, but will lead to long term fatigue.

Language is always a little misleading when describing what we hear.

In the tube world fast would be Telefunken 806S, 803s, GEC CV4085