CPU overload in MainStage 3

Everything is current and up to date. I have a rebuilt 2013 MacBook Pro with 16 Gb ram. 2.5 GHz Intel Core i5. Activity monitor is showing 150% usage and the CPU is maxed out in my MainStage meter. It seems both my piano plug ins are doing it. Im picky about my piano sound and I bought 2 new plug ins. I have everything in the audio preferences set to factory. I tried some buffer settings to no avail. The samples are about 150megs. When I run the plug ins as stand alone apps they work fine at 20% CPU usage. Please help. I have to use this rig live.