I just bought an iPhone 17 Pro Max a couple of weeks ago. My previous phone was an iPhone 7 Plus (that I bought 9 years ago). Mostly I see no speed/smoothness difference between the two EXCEPT every now and again the iPhone 17 Pro Maxfreezes.
My iPhone 7 is 100% smooth. Like I said the iPhone 17 Pro Max struggles not to stutter at times. This is a brand new $1600 phone too! Weird. But, some how I'm not really surprised.
I don't play video games or use resource intensive applications though. I'm sure the iPhone 17 Pro Max is technically faster than the iPhone 7 Plus - But for how I use it (text messages and Discord 99% of the time) I just pretty much see no speed difference between the two. If anything my iPhone 17 Pro Max is slower because it'll freeze occasionally.
I consider that just a $1600 Windows-esque feature.