TLDR: if you've got a bunch of delays in series, for example all-pass filters in a reverb, put them all in a single big buffer and let them crawl over each other for a perf win!
recently I was fiddling around with my hobby reverb code, in preparation for porting it onto a smaller/slower CPU.
I'd implemented a loop-of-allpass filters type reverb, just like everybody else, and indeed, I basically had the classic 'OOP'ish abstraction of an 'allpass' struct that was, say, 313 samples long, and... did an allpass. on its own little
float buffer. (well, short integer, not float, but thats not relevant) I'll write out the code in a moment.
but then I was browsing the internet one night, as you do, and stumbled on this old post by Sean Costello of Valhalla DSP fame - noting the sad passing of Alesis founder and general all-round DSP legend, Keith Barr. https://valhalladsp.com/2010/08/25/rip-keith-barr/
It's worth a read just for his wonderful anecdote about the birth of the midiverb - which spawned the thou