(a) is not an objection because 'life form' is flexible. Any computing sub strait could directly compute say a neural network vs a simulation of a neural network. The simulation will always be slower, but the 'real' version running on "FPGA" or it's higher dimensional equivalent imposes direct mapping between what happens in the 'real' world and what is being computed. EX: If we use a FPGA that's hit by a cosmic ray that bit is flipped, on the other hand if you have an array of FPGA's and compare them then that's decouples the 1:1 mapping creating a simulation but adds overhead.

(b) a simulation must be perfect.

No, if you can get away with a less accurate simulation you can get also get intelligence from less computational power using the same approach in the 'real' world.