Helix Native kills my CPU

I’m on Cubase Pro 9.0.40 and want to use Helix Native for my guitars. The problem is that, even with only two instances of Helix running, my CPU seems to be unable to handle the load. Playback and recording crackles like hell at 256 samples on my Audient iD4 interface, let alone running more than three Helix instances. This does not happen with any other plugin I have. I tried running multiple instances of Helix in Reaper and the playback is absolutely fine, so this must be a Cubase issue. Any ideas?

I have a similar issue with Cubase 10.0.40, Mac OS X, I’ve filed a support ticket.