Waves SSL channel strip causes 'Average Audio-Processing Load' to peak

Help please.

I’ve recently bought the Waves SSL Channel Strip bundle. The sound is great but (almost) every time I move the cursor on and off the controls on the SSL channel strip screen, the Cubase ‘Average Audio-Processing Load’ peaks and the sound briefly cuts out. It’s very annoying and makes subtle EQ and compression adjustment almost impossible.

I don’t have this problem with any other plugins including many waves plugins.

Any thoughts?

Many thanks