last time i use voodoo3-2000 and both game work fine. If i remember correctly then you have turn on(or off) one option when you config Lewpy's glide plugin. You can find down that option very easy when you click button "Explain Setting".
Sorry, i can not point exactly for you because i have just change to Geforce2 MX.
alright voodoo owners........read the readme that comes with lewpys pluggin..... or check the config for the pluggins and check an option, then click on the "explain settings" box.....or try this in the pluggin config
enable experimental flipping(for ff9)
set buffer to read/write
set offscreen drawing to "Full" or "extra"
you could also try to enable emulate mask bit......
The offscreen drawing option can slow down your system....try it first and see if it does.... then set it to "basic"..... its just what I use and everythings works great...speed and effects all come out correctly.... this is for both FFt and FF9...... I also use it for FF8 too.....