2 weeks ago I got myself the new plugin IQ-Reverb V2 from HOFA.
This is a very good sounding IR and algorithmic reverb.
I built a gig with some rackspaces and in every rackspace this reverb.
With each rackspace the CPU usage was increasing…
When I bypassed the plugin, the CPU remained high.
I contacted HOFA and they provided a fix within some days 
Now the actual version is 2.0.4 and is production.
Anyone faced this issue, just load the recent version.
By the way: Gig Performer once more detected issues with plugins and helped the developers of the plugin to improve it