I had a similar situation with that exact iPod and the original iPad mini. They just weren’t meant to handle iOS 9 and it was made significantly worse by aging batteries.
I’d say it’s definitely not as bad as it used to be, today’s devices are far more capable in terms of processing power. For the most part if a device can’t handle a new software feature they just don’t get it in the new update. I’m sure it’s not 100% perfect, and there’s bound to be isolated incidents, but I never had any issues with slow downs on my iPhone 6S or iPhone X (outside of battery problems, which were fully resolved once the batteries were replaced)
At this point the only reason I upgrade my phones is aging batteries and/or dwindling replacement battery support. That being said Apple makes official battery replacements a bit of a pain (which could be viewed as intentional to help encourage new iPhone sales).
I had a similar situation with that exact iPod and the original iPad mini. They just weren’t meant to handle iOS 9 and it was made significantly worse by aging batteries.
I’d say it’s definitely not as bad as it used to be, today’s devices are far more capable in terms of processing power. For the most part if a device can’t handle a new software feature they just don’t get it in the new update. I’m sure it’s not 100% perfect, and there’s bound to be isolated incidents, but I never had any issues with slow downs on my iPhone 6S or iPhone X (outside of battery problems, which were fully resolved once the batteries were replaced)
At this point the only reason I upgrade my phones is aging batteries and/or dwindling replacement battery support. That being said Apple makes official battery replacements a bit of a pain (which could be viewed as intentional to help encourage new iPhone sales).