Windows Vista will improve PC performance by intelligently optimising system tasks in the background, Microsoft demonstrated yesterday at PDC (Professional Developers Conference) in Los Angeles.

Jim Allchin, Group Vice President, Platforms, for Microsoft showed an example of a new Vista feature called Superfetch, which improves virtual memory performance by analysing usage of the system over its lifetime.

"The [current] virtual memory system typically looks [at activity over] maybe seconds and minutes to decide the best usage of memory," Allchin said. "What Superfetch does is look over minutes, days, hours, months, years, and optimises the system based on how it has been used."

Allchin showed an automated script running on a machine without Superfetch enabled which took 36.8 seconds to launch seven common applications. Running the same test with Superfetch enabled reduced the time taken to 10.6 seconds.

Windows Vista will also be able to take advantage of USB memory sticks to boost system performance.

Commenting on the earlier test, Allchin said "Superfetch works great if you have a reasonable amount of memory, and it works fantastically if you have boatloads of memory. But, what if you don't have boatloads of memory? "

"We [considered] a lot of people have these USB memory sticks. I wonder if we could take advantage of those, to make them part of the virtual memory system?" he said.

Allchin demonstrated plugging in a USB memory stick to the test system. "I just plugged in this USB memory stick, any USB memory stick, and as soon as it recognised it, we just got another 500MB of memory on this machine."

The operating system will be able to handle the memory stick being removed without notice and any information written to it will be encrypted to ensure that it can't be accessed on another machine.