Laggy performance is also a result on insufficient RAM. All of your four iPhones (7 Plus, 8 Plus, X, and XR) have 3 GB, which is sufficient for most people... for now.I don't care about geekbench scores or how improved they are over the previous phones. I know I haven't had a lagging iPhone in a few years or more so I'm sure this year will be no different.
One of the great things about Geekbench tests is that they also tell us about the RAM amount. The new R gets 4 GB.
I've already noticed 2 GB devices are starting to lag, and have advised people not to get 2 GB iDevices in 2019 unless their needs are light and aren't expected to change. Going forward it will be interesting to see how fast Apple moves up in RAM specs, but now we are wondering if the OLED iPhones in 2019 will have 6 GB RAM, given that the new XR replacement will likely have 4 GB, and given that there have already been rumours of 6 GB RAM prior to this Geekbench leak. Furthermore, I think it's almost guaranteed that all the new iPad Pros will have 6 GB RAM (or possibly even more in the top end model).