Probably the same type of things that have been brought up in a previous similar discussion at https://forums.macrumors.com/threads/how-many-years-do-you-predict-iphone-x-to-remain-fast-and-snappy.2146752/ would apply again.What do you think?
iOS 12 was the byproduct of an extremely buggy and slow iOS 11. Delayed features like Messages in iCloud and Apple Pay Cash forced Apple to slow down new feature development for iOS 12. I don't think Apple will slow down development for iOS 13 to do more bug fixes.they made an emphasis to increase performance on older devices with iOS 12 and it was a very public thing with the whole battery replacement thing.... I don't see them going back on that with iOS 13.... Even though it might hurt sales I think they painted themselves in to a corner where they have to keep it up now and make sure older supported devices perform well with new upgrades.
To me, it’s not necessary to immediately install updates right away. I like to usually wait a week or more, that way if there are potential issues with the downloads, I don’t want to be the one of those that has a ‘Bricked device’ with my watch or iPhone. And if there is any issues with a potential new software update, Apple usually addresses those right away.The only way if knowing is to let others install it on their phones and for you to await feedback.
I always wait a few weeks before installing big updates.