In Nuendo 6.05, you have to open each and every plugin instance and turn them on or off using the plugin interface.
Or you could link the channels, make sure the inserts are linked as well, and have them all turn on together.
Actually I haven’t tried the second method, not sure if linking the inserts will cover the on/off switch or not.
There is no longer a on/off switch on the mixer interface itself.
Now you only have a bypass switch, which doesn’t release resources.
In bypass mode, the plugin is still taxing the cpu.
You have to open the plugin interface to access the on/off switch.
This is a source of much woe and sadness among the users.
Check out some of the other threads.