Perhaps my advice would be obvious for You, but have You tried to
turn of the doWaitVBlank option in DXDraw?
And another thing, You may be interested in this topic:
http://www.pascalgamedevelopment.com...er=asc&start=0

and this link http://www.micrel.cz/Dx/ for further DelphiX speed up

Regards,
Wodzu

Edited:

I didn't know that Jaro=ijcro so You probably visited those links