Glitching caused by multiple instances

Hello.
I am getting a very nasty problem when I use multiple instances of this otherwise excellent EQ.
It is causing terrible audio glitches - on tracks that are not being processed by the EQ, and they even appear when the tracks with this active are muted, believe it or not.
I cannot even post an audio clip, as attempting to render out causes a CPU overload error in Nuendo, and export halts - right at the point where the glitch happens.
Workaround?
Stop using the EQ. There is simply no other way, and bypassing it or completely removing it gets rid of the glitching - and only this will do the job.
I will try to ascertain how many I can run before this pops up.

It ios not a memory issue or a real CPU issue, as I am nowhere near CPU limit (running at around 19% in Task Manager across all 4 cores - not HT) and scads of physical & virtual RAM left too - almost a gigabyte in each case.