> As for partial writes, I'm not sure if it's backwards compatible to
> turn them on by default, but it might be nice if the option were
> exposed. Partial writes may have less benefit in Python than in C
> since we'd have to reallocate and copy a string instead of just moving 
> a pointer.

You can slice a memoryview() to avoid a copy. But I'm not sure of the point of partial writes here: can't you just send slices that are small enough (e.g. 4KB each)?