I understand mantle says Optifine is not supported, but I would appreciate compatibility with it.

The game exits with a UI crash code when Optifine and Mantle are both installed.

TConstruct_mc1.7.10_1.6.0d40.1
Mantle-mc1.7.10-0.3.1
OptiFine_1.7.10_HD_U_A4

Nope nope and a hundred times nope; Optifine hacks the living shit out of the game, in a way that is not transparent. No support will be rendered, save for "Pester the OF developer for being a moron".