Logic Studio apps Mainstage 2.2 using more CPU than 2.1.3?


My current live setup has been working fine using Mainstage 2.1.3 so when I saw 2.2 appear through the app store the other day I thought it would improve things if anything and just installed it .
However ever since the cpu usage is reading a lot higher even resulting in me having to adjust the latency settings to 256 / 512 from my normal current setting of 128.
Just to double check things I backed up my system and completely wiped it doing a fresh lion install and logic / mainstage right up to mainstage 2.1.3 again and sure enough the cpu usage was back to a much lower figure with the latency setting at 128. So again I installed Mainstage 2.2 from the app store to double check and sure enough with exactly the same setup the cpu idled around 24% which is a lot higher than under 2.1.3.

Hardware - Macbook Pro 13" - mid 2009 2.2GHz, 8GB Ram, 500GB HDD

So... is there actually a problem with drop outs or cpu overloads, or does the cpu meter just display a higher idle amount? Maybe the total processing power taken is less while actually playing, even though the idle amount is higher.
Yeah just to clarify I used version 2.2 live for the first time at the weekend and the cpu usage indicator was really high but having used mainstage for a good while I have tended to ignore it anyway.
What I'm more concerned about is that I started experiencing clicks and dropouts which tied in with the cpu usage indicator being really high.
Fortunately it happened whilst I was sound checking so I ended up sticking the buffer to 512 which solved the problem but obviously i had to compensate my playing with the added latency.
Now having reinstalled lion and logic again and only having installed a minimal amount of plugins exactly the same thing is happening unless I up the buffer?
The most cpu heavy patch I have use's the plugin alchemy whereby I have 2 instances of alchemy layered on the same patch but it was never a problem before version 2.2