A lot of times, it’s the battery age causing this issue though. Once the total battery capacity drops below 80% performance just collapses. Luckily, battery replacements aren’t totally crazy expensive and end up being worth it a lot of the time.
My wife's SE 2020 is on its third battery. It was fine until she accidentally upgraded to iOS 26, but now it's a mega lagfest. Apple's refusal to allow OS downgrades is infuriating, because it's still a perfectly adequate device otherwise.
I’m not convinced that was the issue in this case, as the battery still lasted all day with my normal usage, and the phone became slow overnight after a major OS upgrade.