Can you give examples of how the S7e is noticeably more fluid? I'm likely going to return my Note 7 as well and am curious how/why the S7e seems to be a better phone in terms of performance when they're both running almost identical hardware.
Scrolling is smoother. Stuff (opening apps, switching tasks, responsiveness) just seems quicker. I was one of those people posting in the "this lag is unfreaking believable" Note 7 forum. My lag wasn't "unfreaking believable," but it was quite a bit slower and more stutter-y than my Note 5. I listened to the advice and suggestions of some other users/ambassadors and was able to speed it up quite a bit after doing a reset and not using smart switch or syncing any app downloads automatically. After that, I was more or less content with the phone.
But, after using the S7E, it's just snappier. I really don't understand it either since it's the same hardware, and the same version of marshmallow. The system settings interface is quite a bit different, though, so there are some differences going on somewhere.
Since I have JOD with T-Mobile, I really was just going to use this phone until the replacement N7s came out. But I like it better than the N7 that I had so I'm going to keep it. Please note: I can't speak to the N7 anyone else received and how it may have performed - a lot of people over on the N7 threads reported quick phones. But mine never performed better than my N5 -- at first it was worse, then, after the 2nd reset it became about equal.
Sorry, this still isn't very concrete. Here's one: with the N7, I would notice things like the keyboard freezing and then all the sudden three keys would pop-up/light up at the same time. Weird, glitchy stuff like that.