DX7 performs worse because DX10 cards are optimized for shaders.
They are worse than the old generation at fixed function pipeline applications.
This is no myth nor in any way surprising. This has been known since the GeForce 7 -> GeForce 8 switch which has shown this exact phenomenom as well with older games that are FFP with only very few shaders.
The less shader driven the game is, the better the older cards (X1900 and before, GeForce 7900 and before) will perform compared to the new one.
They are worse than the old generation at fixed function pipeline applications.
This is no myth nor in any way surprising. This has been known since the GeForce 7 -> GeForce 8 switch which has shown this exact phenomenom as well with older games that are FFP with only very few shaders.
The less shader driven the game is, the better the older cards (X1900 and before, GeForce 7900 and before) will perform compared to the new one.