On the A15 running One UI 7, Gallery albums open noticeably slower than on the A03 with One UI 5, where they open instantly. The notification shade also lags on the A15 especially in landscape despite both phones using blur
Disabling animations reduces lag in animations, but there's still a delay between the gesture and the animation. This wasn’t an issue in One UI 5, where the animations seemed to respond faster than the gesture
Haptic feedback when entering the PIN is now missing on oneui 7, WHY?
There's a big delay entering the Recents screen on the A15 from within an app, across orientations. Even a lower-end phone than the A03 performs better. In landscape, the wallpaper and blur glitch.
Also, Recents has wallpaper scaling when entered from an app but not from the home screen. This inconsistency likely contributes to the glitch.
A03 runs on One UI Core if im not mistaken and there is a diffreance.One UI Core is a lightweight version of One UI similar to Android Go which is perfect for budget devices hench is why you noticed better performance on A03
Best you can do if you want best performance on a budget phone is to turn off adaptive battery which trottles performance to increase battery life.This would be a start
