Input Lag And Battery Life
Any time you use a device with a touchscreen, input lag becomes a measurement to which you want to pay attention.
It's difficult to quantify input lag, though. In our tablet reviews, we use a 1000 FPS high-speed camera to measure the time it takes between touching the screen and it reflecting the action. But that only captures the delay of one tap. In the real world, though, second and third inputs often take longer to register.
So, now, we're measuring input lag over successive taps. Frankly, this is probably most pertinent to typing on a tablet's on-screen keyboard. However, it's a good worst-case exercise here as well.
A "bad phone" would demonstrate higher input lag over successive taps. Clearly, that's not what we see here. Despite the fact that Nokia positions the Lumia 710 as a budget-oriented smartphone, we're impressed with its responsiveness.
The only caveat is that lag does increase when CPU utilization is already high. For example, it exceeds 300 ms if you try to scroll when the ESPN app first starts up. We're curious to see if the Lumia 800 exhibits different behavior. Though its internals are very much similar, it's possible that the AMOLED screen could yield dissimilar results.
Our cellular battery life test is pretty straightforward. We record two sides of an actual conversation, call a POTS line, and play each unique side back through the phones in 90 second intervals until the mobile device runs out of juice.
Although the Lumia 710 ranks behind the iPhone 4S and Galaxy S2, the result isn't bad for continuous talk time. Nokia's official specs put the phone's standby time at 400 hours.
We're still undecided as to how we want to measure battery life during Web browsing. Should our benchmark involve rendering a graphics-heavy website like cnn.com? What about something text-heavy, such as Wikipedia? Should we play MP3s in the background? Sound off in our comments section and let us know what you'd like to see.