I sort of doubt your individual ROM is the source of any sound issues; the sound support in Basilisk is a "synthetic" 16 bit sound port that doesn't actually closely emulate the sound device in any actual 68k Mac so the ROM is sort of irrelevant. (They did sell 16 bit audio cards for NuBus and LC PDS, I suppose it's arguably close to having one of those.) I'm pretty sure, in fact, that the Performa ROM is the "recommended" ROM for Basilisk in some circles because it has some bugfixes relative to earlier Quadra ROMs.

Alas I can't make a positive suggestion beyond that, Windows ain't my bag. Whatever it is it's something "Windows-y". On Linux or Mac I've never noticed anything worse than the occasional lag. And heck, I've seen lags like that on real 68k Macs.