Looking at a 100mb multipart upload I can see that email module takes 3.7s and allocates 265 extra MB to parse it, while flanker.mime takes 0.22s and allocates 0.2mb extra memory.
I'm a corelibs nazi and refuse to add dependencies to the very last when I'm writing Python.
But if what you're saying is true then I can see a very good argument for replacing email with flanker.
Python has already simplified programming so much coming from languages like C, so I guess I view it as a tolerance matter.
I'm willing to put up with the longer way of using corelibs in some cases, to keep my dependencies low. And I'm willing to tolerate this longer way because I feel that Python in it self is such a shortcut from other languages that I'm already reaping huge benefits.
I know there's usually a huge community testing and supporting all dependencies but having installed some Ruby and Node apps I've seen massive lists of dependencies and I've had situations where it breaks down on some obscure library used to do some really mundane task.
I could not have solved many of those cases without the years of Linux experience I already have. I don't think users should have to go through that.