Vista's user interface suffers from more "friction" than its predecessor XP and is actually a step back for Microsoft in its pursuit of Apple's Mac OS X, an analyst has warned

In an extension of research published last year, French analyst Andreas Pfeiffer oversaw testing of what he calls "user interface friction", the fluidity or reactivity of an operating system to commands. He likens user interface friction to the reaction -- fast or not – to stepping on a car’s accelerator.

"We realised that there are many things you don't easily capture when you do normal benchmarking, such as elements in the user interface that slow down the user," Pfeiffer explained.

Pfeiffer compared Windows Vista and Windows XP against Mac OS X using benchmarks for menu latency, common desktop chores and precise mouse positioning.

"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."

Pfeiffer’s new data on user interface friction put Windows Vista, and its Aero graphical interface, behind Windows XP. Menu latency remains a major problem in Vista, which was 20% slower than XP, Pfeiffer said. "Windows XP was a major step forward from Windows 98, but Vista is back to where 98 was," Pfeiffer said.

Vista running Aero was 14% slower than XP when measured on common desktop tasks, such as opening a folder or deleting files. Vista also lagged behind on mouse precision.

Microsoft declined to comment on Pfeiffer's Vista user interface research.