Nevermind, turns out I had it set to preload all audio sounds (and I have a lot). Turned that off and now it's speedy quick
UGH, but now in Chrome the audio is all delayed by about 5 seconds!
Edited to add (if anyone reads this and cares) that preloading the audio that I need in a layout at the start of the layout, then it works in Chrome. Note that I'm using the latest release R259.