While we normally reserve 3D WinBench 2000 for our illustrious video card reviews, we have also found that the included processor test is quite useful to stress the architecture of today's CPUs. Games have historically been very sensitive to L2 cache speed rather than size, so the brief game scenes from WinBench 2000 run on a "null" software renderer makes for a good benchmark of internal processing.
The 50MHz jump from the Duron 850 does not add a tremendous amount of horsepower, but it does serve to widen the gap between the top-end Duron line and Intel's fastest Celeron offering.
As a supplement to 3D WinBench 2000, we have also run MadOnion's 3D Mark CPU test, which focuses on the floating point-intensive geometry portion of the CPU. Rather than using hardware T&L, each CPU was set for its respective pipeline optimization (SSE and 3Dnow!).
Mirroring the results we saw in the 3D WinBench processor test, the Duron 900 pulls just slightly in front of its predecessor, the 850MHz chip. Even still, the gain is enough to emphasize the Duron's dominance over the Celeron in terms of performance.