[digg=http://digg.com/microsoft/FUD_Research_shows_Vista_interface_slower_than_WindowsXP_and_MacOSX]
I came across this story running on MacWorld, claiming that the user interface in Vista is slower and hence a step back from Windows XP. Because of the latency the researchers say that Windows Vista interface is where Windows 98 was!
To quote from the article:
""Menu latency is the time it takes an operating system to display a menu,” said Pfeiffer. “In Windows, it’s not immediate. That’s not a speed or performance issue, but a design choice.”
The new UIF data put Windows Vista, and its Aero graphical interface, behind Windows XP, which had showed improvement over earlier Microsoft operating systems. Menu latency, Pfeiffer said, remains a major problem in Vista, which scored 20 percent slower than XP. “Windows XP was a major step forward from Windows 98, but Vista is back to where 98 was,” Pfeiffer said."
First I wondered, after having used Vista myself I found no discernable difference between either Windows XP or Vista operating system. I investigated in which workstations the tests were conducted, according to the full PDF report, the following systems were used:

The Dual 2.8Ghz Dell Dimension, I googled for it and came acroos this: The Dell Dimension 9150 a 2.8 Ghz Dual Core machine, according to the official Dell website at here, this is a Vista Capable machine, which according to here in the Dell website means: Can Boot the OS but without running any applications or game! (see this). So hardly a system which would run Windows Vista at its optimum speed.
The Dell XPS 3.2 Ghz Machine however, is an optimum Windows XP machine: With 3.2 Ghz Pentium 4, 256 MB RAM (in standard configuration). I dont know about the Mac workstations so no comment about them.
So this hardly looks like a fair comparison, I would like to see a test where all operating systems are run on optimum performance.