Android's horribly laggy UI? Which phone are you using? My Pixel 1 is smooth as silk, no performance degradation at all after one year of use.

In Developer Options, set the animation duration to 0, which kills the animations. It's like having a brand new phone not having to wait for stupid animation fluff to complete.

Take care though, because I've used an app in the past which was broken with animations disabled. I can't remember which one it was, but it relied on an animation completing to trigger an event when a soft button was held down for a certain interval.