Since the commands are executed at the speaker, and the controller is mostly just a presentation layer to the application running on the speaker’s computers, most speed lags tend to be caused by wifi interference , either between the controller device and the router, or the speakers and the router.

Beyond the data in the linked FAQ, there is also a smaller opportunity for duplicate IP addresses causing intermittent connection issues. This can be tested and ‘fixed’ in the short term by refreshing the Sonos network. Unplug all Sonos devices from power, then reboot the router. Once the router comes back up, plug back in the Sonos devices. Wait a couple of minutes, and then test. If this does fix the ‘lag’ issue, consider researching in the router’s manual on how to set up reserved IP addresses, which would keep the situation from recurring. 

But still, there is a certain amount of processing to have that presentation on the device, so it is conceivable that the display of the information is slightly faster on newer devices. But wouldn’t hurt to check how many apps are running in the background, and try a reboot of the device, to see if that helps. Older devices do have older CPUs and display capabilities, there’s no way around that. 

One of the few things that involves non-trivial network transfers into the app is album artwork. Some artwork comes direct from the music service (ie app->music service->app) and some comes from the speaker (app->speaker->music service->speaker->app), it varies by service. Common to all of this is the speed of the many network hops, when wireless especially. All artwork is cached in the app, so if one device has already “seen” an album it will be quicker then another device which has never seen that album.