Mario Party core slowdown

When I tried Mario Party on PJ64 1.3 (Jabo 1.2 D3D & DSound, N-Rage input plugins) I get a steady 50-60VI/S during the short black start, but it drops to an average 23VI/s just before the graphics come up. However, it runs full speed on 1964 just fine, so is it just that my CPU isn't powerful enough for PJ64's emulation of it?

Specs:
Duron 800
128Mb PC100 SDRAM
Voodoo 3 3000 16Mb
SB PCI128