adef, Logic works this way. Every singel channelstrip has to load all plugins on one single core, so if you are working with just one channel strip, you will see an extremely unbalanced load, but in an ordinary popsong there will usually be more one track, let´s say 8 tracks...now...the load is spread over 8 cores...
It is that simple. The turorials in this subject is just confusing. If you are running out of power using only just one channelstrip there is something wrong with the plugins, update to latest versions. The Apple "workarounds" are just piece of crap. Not from real life scenarios. If you have to do such a foolish workarounds you should have an 8 core 0.4 ghz computers which does not exist, exept in laboratories from 1996.