The Stamina / Speed option switch that is so unique to Sony SZ laptop. The same image is almost shown on all SZ laptop review.
Sony SZ series is one of the few if not only laptop to offer a choice of 2 graphic subsystem to choose. With the SZ55GN it is either an Intel X3100 or Nvidia 8400 GS.
Obviously the X3100 mode would be the one for power saving and I must say for most day to day work it would be sufficient. Having a Windows experience index of 3.2 for desktop performance and 3.4 for 3D game, I would say it would be sufficient for most casual games.
The onboard Nvidia 8400GS gives a better score of 3.5 for Destop and 4.7 for 3D games is not blazing fast coupled with the decision of Sony to limit the memory to 64M seem to cripple the 8400GS. But I must say the real benefits come from the fact that dedicated graphic and memory free up system resource from accessing memory at the same time hence maying the system more responsive. That is why most server come with a dedicate graphic card which is only good for 2D acceleration.
The dedicated graphic is a real boost for games like Need For Speed or warcraft but I would not recommend games like Crysis.
For general office use, word, excel or even powerpoint there are little to differenciate the 2. Especially when there are few application open.
Power Saving from switching to the Intel 3100 chipset gives me about 30min to 1 hours of extra time on the road which is pretty much handy. Watching full screen DIVX movies with this consume ~50% CPU. While switching to the 8400 CPU utilization is about 30% under the same setting, Maximum powing battery mode.
I do not know what other power saving feature in enable which I switch to Stamina mode but the system is definitely more responsive using the Speed mode.
Unfortunately, the system does not allow switching on the fly and users would need a system reboot to switch between the 2 modes. Which I feel is a big pity. I used would like to switch to Stamina mode when I leave my desk to proceed to the meeting room and vice versa but would be stuck in the same mode unless I do a system reboot. Currently all I would do would be to do modify the power plan that I am on. A utility that could set the power plan when I switch from Stamina and Speed mode should be given at least. Why would anyone want to use Max Performance under Stamina mode or Max battery under Speed mode. to switch between the 2 extreme a user would need to set both item and do a system reboot.