My early 2015 Macbook Pro can be a little sluggish when I have lots of stuff open on my 4K monitor, but I think it'd be a little harsh to judge a six year old machine for that! This laptop's done very well really, it's definitely going to have an afterlife as a media server or something after it stops getting macOS updates because I'm loathe to get rid of hardware that's still doing a fantastic job.