I installed MS3 and I noticed a high CPU consumption!!!

Sorry to ask: but besides the CPU meter, what is the _actual_ problem? Do you have audio dropouts?

I too noticed the CPU meter all over the place using MS3.

BUT...

I just did a several gigs this weekend using many of the same plugins I've always used and noticed no dropouts or sluggishness, regardless of what the CPU meter reads. Maybe it's just some kind of anomoly.

I was using several instances of Omnisphere (a well known CPU, disk and memory hog), VB3 through MetaPlugin and jBridgeM (just to be able to use the 32-bit plugin without crashes) and Addictive Keys for the grand piano.

All good.

It's worth noting that one difference with the Quck Start Keyboard template in MainStage 3 is that it includes multiple Space Desginers. The template in MainStage 2 did not. This plug-in will definitely have an impact on the CPU.

I am experiencing all sorts of illogical CPU peaks. Playing a Mainstage Vintage piano patch without any effects can cause the peaks. This happens if I am using Omisphere, any patch in Kontak, Truepianos. When I was using version 2, I knew that by limiting and careful choice I could still use 2 or 3 patches of the AUs I have mentioned. Now, it just seems anything can trigger peaks. Thankfully, I only experience a quick drop out. The metronome continues to keep time and I don't experience sudden latency as I would with 2 when it hits the peaks. With audio drop outs, people tend to look for the sound man. Ha.

Regardless, it is still a problem I would like resolved.

Just a quick tip for finding the CPU hog, you can double click the CPU usage meter in the top bar and it will display a usage meter showing what plugins / instruments are consuming power. I had 3 instances of space designer running and was getting overload messages all the time with the buffer at 128.

I found using Space Designer on a Aux channel strip and just routing audio from individual channels (via aux send) as required seemed to be the only way my laptop handles the CPU usage (2.66 core 2 duo), pitty because it would be nice to be able to run at least a few different reverbs at the same time.

I also noticed from your earlier screen shots you have Google Drive / Dropbox / Skydrive running, if your needing to save some more power you could also quit those things, and I know their only small amounts but every bit helps.

You could insert a different reverb plugin like the platinum verb or spring reverb -- almost any other reverb will use less CPU.