here is an update after a day trying to solve that problem :
my config : 3.2Gz HT, Sapphire ATI Radeon 9800Pro 128Mo, 1024 Mo RAM
Ht is disabled ; I have Catalyst 4.8 drivers ; i did delete F1STATE and F1GRAPHIC files
The original game running with the sound hardware acceleration set on none, I have about 17fps and PO is about 100(starting Grid), 80 in race with high details set in the game (in the graphic option menu).
The same config. with updated 2004 cars : PO 130(starting grid) and around 100 in race.
Now, I have with the F1graphic from FortKnox (the quality one), here is the result :
with the sound acceleration set on none : 30fps, PO is around 50 to 60
with the sound acceleration set just one after none (the minimum one...) I have 11fps and a PO around 150 up to 300!!!!