Just a pic

[The_Doctor]

Ok. For likely wrong reasoning, that made me think of how easily the energy seems to go out of a bass guitar string if the pitch bend is down, not up, but if the thought is valid it may mean that spreading the duration of any short hard transient involves heavy losses in any system. In audio we ignore it only because we have easy amplification.. Maybe a better analogy is reverb, but again, more diffusion to spread the pulse energy in time means more losses.

EDIT:
PSUs also used to be very inefficient, by making SMPU's the much faster cycles meant smaller and much more efficient lengthening of pulse shape to smooth it could be done, with vastly lower losses. I know that reaching for analogies like this is maybe not the best way to understand the laser, but it does seem to imply that heavy loss is inherent to maybe any system that tries to get smooth output from a series of large, sparsely spaced peaks of power or energy.

[shrad]

the efficiency must be ridiculous compared to the input power...

I have always wondered if SFG could be done "at home" easily... I guess you need pulsed operation with decent peak power to get anything out of it...