Waves Electric88 - glitching in GP but fine in MainStage

I’m currently rebuilding an oversized MainStage concert into a downsized version in Gig Performer, and it’s been going ok, but I just encountered this strange issue. I only had one instance of a Waves plugin, the Electric88, and one instance of THU (that only has 3 effects in it, so not much going on there at all)

CPU in the top right of GP was hovering around 14%, going up to around 20% when I was playing. But then once I was playing more than 5 keys at a time, CPU jumped to over 50%, and I was getting clicks and dropouts. I bypassed the THU patch and it was still doing it, so I think it must be the Electric 88.

Just out of curiosity, I saved my plugin settings and made a brand new MainStage patch, with one channel strip, with my exact same Waves and THU inserts. Played totally fine, no glitches, no clicks. Then immediately going back to Gig Performer and it was glitching there.

Any ideas what would be causing this?

What is your sample rate and buffer size in each of those applications?

Also, in MS do you have the “Safety Buffer” enabled?

Can you upload the rackspace?
I have the same plugins you mentioned.

Ahh, good question! MainStage says 64 samples (I/O Safety Buffer is not enabled), and GP is 512. You think those different numbers would do it?

Did you use the AU version of Electric in Gig Performer?

If it works in MS with 64 samples, then it should absolutely work with GP at 512 unless the waves plugin itself doesn’t support that buffer size — try changing the GP sample buffer size to 128 (say)

But what sample rates do you have in each application? And what is your audio interface?

And yes, you should try the VST version rather than the AU version (but let’s change one thing at a time.