Multi-Camera Setup

I am trying to setup a two camera setup with BoinxTV using a brand new Mac 8-core, the newest graphic ATI Radeon card, the internal firewire, a separate PCIe firewire card and two JVC GY-HM700U’s. I can get them both up and switch with cut as the transition. However if i switch to dissolve it freezes a bit and and continues. the rendering jumps to over 100%. What can I do to fix this?

Do you use the video switcher layer for switching? If not, please do so.

Could you point me to documentation on this?