I have already heard about this problem... I don't have it, it's always very fluid and lag-free, but I remember I noticed kind of reduced framerate once or twice soon after the update while scrolling the homescreens and I thought "that is weird". Well, as usual I did a factory reset after the update and so long, no problems. Did you try that?
it is weird that some is having the issue, while others are not... the hardware is supposedly the same... could it be some specific combination of running apps? I hope we will hear an official answer soon.
Ok, I think I understand... I locked and unlocked the phone rapidly and consecutively 3-4 times and I also could observe what I call "slugginesh" in scrolling homescreens/apps... then I locked the phone again, waited around a minute, unlocked again and the "slugginesh" was gone.
I then tried to turn off the glance screen, and it never did it again (locked and unlocked several times), then re-activated glance screen and it did it again.
I guess it has something to do on how glance screen work, since when you unlock it takes like half second for the glance screen to appear and then, if you suddenly unlock, probably something is still running in the backgroun... that is what I could guess.
You could try the same experiment. Turn of the glance screen and try to replicate the situation where you notice some loss of fluidity.
I usually never lock/unlock my phone consecutively, that is not my typical usage, so that is why, a part from now, I never noticed it.
I also have this problem.
It started after the Oreo update, it was also present on the Beta which is why i switched back to Nougat back then, but now it's pretty annoying on the "stable" build.
It randomly happens upon unlocking the phone. The phone itself isn't performing the tasks slower but rather the interface slows down which seems to be a graphics driver issues. I've played around with the developer options enabling GPU acceleration for 2d interface actions etc but that didn't help, changing the OpenGL rendered also didn't help. I've mentioned this through live chat via the support app and the person at the other end mentioned he would let the devs know, so fingers crossed.
try to turn off the glance screen. It solved the issue to me. I think the glance screen in Oreo is not working properly. In Nougat it also increased the counter when messages from other app like telegram, whatsapp, hangouts were delivered. Now it doesn't...
I can also confirm this issue and this has something to do with the glance screen options.