[dversion]

Open Activity Monitor and check out the "kernel_task" CPU usage. Using Thunderbolt tends to activate thermal throttling on Intel chips and basically the CPU is occupied by "junk" instructions to occupy some of it's processing power in order to keep the temperature down. Apple likes to operate well within the Intel spec for CPU temps.

Myself, I bought a new MacBook Pro and an external PCI thunderbolt box with Native card and two external monitors daisy chained or running on Thunderbolt. I was upset to find out that CPU takes a huge hit running this way and temps spike quickly. I'll have to look into a Desktop solution or one of the newer 6 core CPU's to be able to run the system with a medium plugin load.

I downloaded iStat pro to keep an eye on things like CPU temp which helped me analyze some of the hits to the CPU as I attempted different daisy chaining configurations.

Hope this helps someone...