Just out of curiosity, which tasks do you perceive to be slower? I am just curious where you notice it.
I am not a super creative type so I don't do a lot of video/media stuff.
Most of what I do is web dev and testing.
Obviously some full clean Xcode compiles take incrementally longer but that doesn't really matter as I don't do those all the time.
Starting up the iOS debugger is def slower than on the Macbook but still quite usable.
Some SoapUI regression tests bog down when I am running lots (>10) concurrent service tests.
I have also been used to getting really lazy about running VM's in the background and not pausing them. Sometimes 2 at a time. I feel like I have to be a tad more aware but thats not really a bad thing.
There is nothing that "just doesn't work" or is so slow its unusable. I am more than capable of making my high spec MBPro run like crap after I abuse it long enough. I think the threshold here is just lower.
Non work - I am playing Beyond Earth just fine - keeping settings reasonable and not trying to play epic campaigns but it works great.