you can easily reproduce this test with this attachment file Test A
- i load 6 "play.VST3" in chanel rack Just load the plugin, "play" don't need to load an intrument in for this test
- i make 6 automationclips - midi cc11 (Exp)
- i load 6 "play.VST3" in patcher Just load the plugin, "play" don't need to load an intrument in for this test
- i make 1 slider activated in patcher
- Link to cc11 on 6 play instance in patcher
- i make 1 automationclip - patcher slider
A ( CPU ~ 20%)
B ( CPU ~ 95%)
I don't know if this issue exist with vst2 or any other plugins.
Regards