GSX is not stuttering. In fact, it's exactly the opposite: it's now more respectful of other addons you might be running.
Simconnect addons usually connects to the sim at each frame which means, the more frame rate you have, the more traffic is created on Simconnect. This gets worse if you have many add-ons because, if each one requires frame by frame updates, the impact of having an higher frame rate will be increasingly bad on Simconnect connections, up to a point that addons can start to cause an impact TO the sim and to the other add-ons too.
So, in order to be better citizens and more respectful of other addons, instead of trying to take every frame for ourselves, we added a frame rate cap. Since GSX animations are made at 30 fps, it would be totally useless requesting updates more frequently than that, so we capped the update frequency at 30 fps so, having an higher frame rate won't spam the sim with data request any higher that it should.
So, this was obviously made intentionally, to behave better.
But the downside of this, is that if you have ANOTHER addon that is spamming the sim with data requests, since GSX is self-limiting now, it's possible this other addon is now getting more updates, so GSX is suffering FROM that.
In an ideal world, the sim should offer a framerate-capped way to get data, so all addons would get an equal change to refresh. But unfortunately, the highest fixed frequency update is at 18 hz, which is not enough to represent 30 fps animations, and the next one higher is "unlimited", so it has the issue of causing too much data transfer, the higher your visual frame rate is.
We'll probably add an option to disable this feature, so you will be able to tell GSX to just don't care about spamming the sim and possibly distrupting the other addons, but it would likely get smoother itself.