Mantle on the 7970m crossfire

Hi,
I know mantle has been out for a while but I just noticed that my BF4 was running with DX11 enabled all along.
Now I switched it to Mantle and the performance is actually much worse with a lot of lags.
Does anyone know if the 7970M does actually support Mantle?
Is there anyone here who tried it and for whom there was an actual performance improvement after enabling Mantle?


Thanks guys!


Cheers

Chrusti