My CUDA program uses only float, int, short and char types in its computation. None of the input or output arrays have members of type double. And none of the kernels create any double type inside them during computation.
This program has been compiled using CUDA SDK 5.5 in Release mode using NSight Eclipse. A typical compile line looks like this:
nvcc -O3 -gencode arch=compute_35,code=sm_35 -M -o "src/foo.d" "../src/foo.cu"
I am running this program on a GTX Titan on Linux. To my surprise, I noticed that this program runs 10% faster when I enable the full speed FP64 mode on Titan. This can be done by enabling CUDA Double Precision option in NVIDIA X Server Settings program.
While I am happy for this free speed bonus, I would like to learn the reasons why a CUDA float program could get faster in FP64 mode?