Complex sentence: Two comparisons have been drawn between CUDA and OpenCL since its inception, and both arrived at the same conclusion: if the OpenCL implementation is correctly tweaked to suit the target architecture, it performs no worse than CUDA.
Split into simpler sentences: Two comparisons have been drawn between CUDA and OpenCL since its inception. They both draw the same conclusions: if the OpenCL implementation is correctly tweaked to suit the target architecture, it performs no worse than CUDA.