Going by what I've seen, the performance changes can't say one hundred percent yet because of the biggest elephant the the room many many many many many many many many many many and many players still downloading. So that will be impact performance right now. However I noticed when I sprint I move more like I'm sprinting from before it didn't feel as if I was sprinting. Here is the thing though, I play on a laptop intel core i3 seven gen. So my specs might be what people call crap. Well maybe better then other specs out there for sure but still possibly not the best that means I get lower fps, but I think as more people finish downloading it will go up a bit. Fps it seems to be determined on the area, so it fluctuates. Once the majority of people are done downloading. I think the performance will be better. I played a couple of battle grounds first one I did it was really laggy for me and the second wasn't as bad. Typically it isn't as bad or noticeable. But I do think you won't see the improvements in full till all the major bulk of the downloading is finished.
Some of the things Zenimax seems to be doing to fix performance along with the stuff they have already done.
One seems to be fixing Desyncing also known as Animation Canceling. For those that don't know and might ask what is a desync, its another term for lag they are one and the same. An example your playing a video online whether it be a youtube video or a tv program on the net say like for example Ncis on Cbs. When videos are synced the communication for the client your computer and the video plays smoothly. However when a video desyncs then it goes for a bit but then stops and a round circling thing appears on the video like its loading up, sometimes it might last for a 30 seconds of the load icon and then it starts playing again. Maybe it goes for a minute maybe thirty seconds then the video stops and the loading circle thing appears once again, that is a Desync.
Without animation canceling when you are casting an ability allowing the animation to play out the animation plays out and communicates that action to the game server from your client the combat seem more slow but it goes through and the game is more synced. When you animation cancel, you are tricking the client into canceling the animations what this does is tell the client that the damage has been casted, you are then creating a desync between yourself the servers and not only the servers but other players. So it seems like your doing more damage, and the client communicates that but the client is still sending the communication to the server in a desynced state. When desyncing it seems like you are killing things faster and you are.This is a beneficial desync because you are technically duping the damage by tricking the servers to calculate more damage then the ability is worth .
So when another player kills you you might see in a death recap a light attack two snipe attacks. They used snip once but because the data is so inaccurate, you are not getting the whole picture of whats going on. So the client and server lies to you. Now why damage might duplicate is the same reason why the Forums duplicate threads if there is latency when posting a post here. Often when someone creates a thread they somehow create a copy of the thread. I think this same thing is happening on the server when it comes to damage as desyncing/lagging the client and the server allowing for this to be possible. Just like what happens here on the forums. So what you are doing is lagging yourself and others and they are lagging you in return to do more damage and have faster combat. The more desyncs there are the worst the performance becomes for everyone. More people whine and those same people are likely doing the most animation canceling.
So what are they doing to fix this one is making communication to the server first priority so communication comes before the animation that is the shield changes. Instead of the other way around so like Vampirism I think they are flipping the dynamic and might do that with other aspects like weapons. So there is better overall communication and less desync. In turn this causes animation canceling not to be as effective if at all. Because now you are blocking damage before seeing the blocking animation in lag filled environments. At least that was how it was explained by Gilliam.
Here is the thread with the video so you can see for yourself.
https://forums.elderscrollsonline.com/en/discussion/511531/how-the-new-block-is-system-going-to-work-explained-by-zos-gilliams-livestream-twitch-video-clip/p1
He also explained the Desyncing causes people to move around on the ground as dead bodies to other people or yourself. It also causes the annoying death screen bug that happens when you resurrect only to reapaer in the death screen forcing you to either have to relog or reload ui. That is another Desyncing issue and its caused by animation canceling. They did say they are not fixing the running on horse issue but i think the desyncing plays a roll in that bug so it might be reduced if they get around to fixing all the desyncs caused by animation canceling.
Other methods to fix or discourage animation canceling is what the cast times are for. What cast times do is when you try an animation cancel certain abilties before the cast time is up for them they won't fire and they will actually be canceled out and you get refunded. This is a stop gag measure and the reason why they might have added those in to begin with. We for sure are going to see more of these cast times being added to normal abilties like they did with the reworked dk ability. If every player in the game came onto the forums and said no more casting times they won't listen on that one and for good reason they got performance to consider. Animation canceling is causing desync aka lag they are fixing or reducing the lag and as such fixing or reducing the animation canceling. So the less animation canceling the better the performance.
Second type of fix they are working on is rewriting how Aoe abilties work with the game client and servers. Another source for lag, in this game they said it won't fix all of it but will help. They mentioned working on this during the Greymoor live stream. So Aoe is going to be overhauled and that will be part of the overhaul reworking of the games combat system in this game. Which will include the Cp system, what they are doing is small changes right now and only just starting with it.
By doing all these overhauls of the game they are fixing a lot of the performance issues. That is their goal so they are not just stop gagging anymore they are actually working on fixing it. They are also adding in the cold storage for accounts on the Na/Eu servers that way the servers don't have to calculate them even if they are not logged in. This will also really help performance that is why they are doing this.
So gist of the changes meant to fix performance.
1. Fix Desyncing/Animation canceling by reworking how the games combat system works or adding in more cast times.
2. Reworking the Aoe damage/healing and their impact on performance.
3. Cold Storage for inactive accounts.
4. Combat Performance Overhaul/Cp Rework.
Once all the rework is done the game will be a lot better for players and more enjoyable. At least when it comes to performance maybe not so with those that like fast and fluid combat.