Twisted Deferred.addCallBack() vs. yield and @inlineDeferred
The differences should really be subtle. If this code really does run that often that it matters, perhaps you should look into your application design. Otherwise, take the variant which is more easy to read, you will have to make heads and tails out of it a couple of months or years down the road.
EDIT: If you really want to know, here is how you find out (it could, after all, be implementation specific to your python version): run both version in a tight loop and measure the time. Increase loop count until the time difference between the versions is far greater than the time variance of the same version across multiple runs. Repeat after changing python version, OS etc.
Is there any reason to use one over the other?
Do they have the same performance?