According to Sony, the the camera (P&S) records video using AVCHD, which is a highly compressed format and very taxing on the CPU, especially with a resolution of 1920 x 1080.
But even my C2D 2GHz iMac is capable of viewing H264 encoded video in 1080p without lag, and H264 is used for AVCHD footage anyway.
Did Sony deliver any software with the camera?