CPU, much like PS2 EE's 66 million.
as for actual polygons pushed to the screen, I heard DC's upper limit was 7 million. obviously that is peak. real in game figures were something like 4-5 million. but only 2-3 million in the average DC game, as DC was never really pushed to its limit given its short life.
Indeed it is not bad. the original figure for Dural/Katana was 1.5 million polygons in 1997. Sega's official figure was "over 3 million" in 1998-1999.