DOES your favourite app seem to be taking longer to load than it used to? That may be due to ever-richer graphics and overloaded cellphone networks, which take their toll on smartphone apps and increase the time they take to boot and retrieve information from the network on, say, train times or the weather.

A way to make them boot faster, developed at the University of Massachusetts at Amherst, could mean your app might one day be ready and waiting for you the moment before you need it.

Tingxin Yan and colleagues have borrowed a trick from computer science to achieve speedier loading. Called predictive caching, it involves guessing which software routines are most likely to be needed for the next stage of a computerised process - so that the right app is primed to run when called on, without booting from scratch. The system uses the phone's location and motion sensors to learn when the user typically runs the app, Yan will tell the MobiSys conference in Windermere, UK, which starts on 25 June.

Imagine that, as you walk to a railway station each day, you normally get to a certain street corner and open a train times app to see if the trains are running to schedule. The software checks the time you usually do this, senses that you are walking and preloads the app, with the current train info retrieved by the time you arrive at the corner on which you normally request it.

In tests, the software cut 6 seconds from the average 20-second boot-up time for apps on Windows phones - although it gobbled 2 per cent of the battery per day while doing so.

App author Peter Bentley at University College London sees issues. "This works great if the things being cached are entirely predictable. But what happens in an emergency when you need to use a rarely used but essential app and the phone has preloaded lots of massive apps which then have to be cleared first?"

It would be better, he says, if coders designed apps to boot faster in the first place. It also depends on the type of app. "I would see this technology better suited to those apps that are designed to be used for 30 seconds or less and which need to go online and download/upload new data."