Sonar X2 with Fxpansion Tremor: not using 64bit/all cores?

I'm using Sonar X2 with Fxpansion Tremor drum synthesizer. The sound is sometimes distorted. When I look at the Performance meters, memory use is low but strangely, I only see one single bar on the CPU meter, wich sometimes turns red on the top. If I use other plugins, all bars are shown. Is Tremor not using 64bit or all cores? Any tips? LeC0mte Windows 7 64bit Samsung RC530 laptop with Intel Core i7 Sonar X2a