trouble with audio output from several voices

Hello,

I made a 4-voice FM drum machine in Max last week, and since yesterday I've had issues with one voice at a time dropping out after its first few beats. My sequencer is working as designed, and my (somewhat crude) FM algorithms are working too, but sometimes an svf~ or abl.device.limiter~ stops producing output altogether.

This sucks!

I'll open the problematic subpatcher to unpatch then repatch some stuff.... then the sound comes back! And then it goes away again.

Sometimes, say I have a hihat sound going.... I'll turn on my kick drum and all audio stops. It's like I'm hitting a processor ceiling or something.

As you can imagine, this has been very frustrating. I researched all of the scheduler and audio settings and adjusted them back and forth and nothing seems to help. Is the issue just my 6 year old Mac running this huge patch?

Any insights would be deeply appreciated. Thanks!