Flash will cause 100% CPU usage because of the nature of flash and multimedia in VDI/VMWare. I can't give you the exact technical reason, but VMware VDI cannot handle multimedia very well unless it is using the MMR, which currently does not handle flash. Wyse will be releasing Flash Redirection inside MMR very soon, which will lower the CPU usage. I currently have the beta of the product, and CPU usage is not at 100%, but it is not at 0% either. It still uses some CPU usage. It may get better with the PCoIP protocol though when not using RDP.