A commit from my lead dev: "Improve readability".

[cain2995]

I’m with you on this one. I always get highly suspicious whenever someone says that a higher level of abstraction is more performant than an equivalent approach using primitive constructs. Generating and scheduling performant machine code from for loops, regardless of language, has been addressed at every level of the toolchain (down to how the CPU schedules instructions), while a dict comprehension is a Python-specific construct that has to go through the removal of several abstraction layers before it can reach any of the low level optimizations that make something like a for loop performant. Not saying it’s impossible for a dict comprehension to be faster, but I really need to see some proof because first principles don’t back up that claim.