Vista - VPC07SP1 + Windows 98 SE - very slow frame rate

When trying to run an old directx 2.0 game in Window 98 SE in VPC 2007 SP1,
the frame rates is less than 1 per second. The host system is XP Pro SP3, and
it's fairly fast, Intel Extrem Core 2 X6800 cpu, ATI HD2900XT PCI express
video card.

I turned off the network adapter emulation (it didn't work anyway), and the
other ports default to off, and I assume that less port emulation helps.

I look at the VPC stats and the frame rate shows as about 53, then shows as
about 38, but the actual frame rate is less than 1.