With a 400MHz clock speed you would expect a speedier device, however on an overall basis the Treo Pro felt slower than its recent counterpart the Treo 800w with its 333 MHz chip. Overall performance is acceptable, however certain functions occasionally cause the device to slow down at times, usually when browsing the web. Windows Mobile can be somewhat demanding and it seems the device has a tendency to get caught up at times with some more intensive tasks. I also had trouble with the responsiveness of the onscreen soft-key to answer phone calls, but using the green “orb button” instead alleviated that. Its certainly not pokey in daily use, but in general it just doesn’t feel as finely tuned as the 800w.