From the Developer’s Kitchen: Widgets and Resources
Depending on what they’re doing, widgets can be resource hogs. A home widget is essentially a small and limited user interface to either an existing app or background service. They’re primarily used to display data, not for input, which can be a challenge for apps like our notes widget which is in development. Since widgets are typically displaying data from a background source, they have to be updated at regular intervals…for example with a stock ticker app, it would be every second, using lots of resources. With our notes app, it only updates when a note is added/modified so it is relatively lightweight. Our upcoming gesture dialer/text widget Sign is also very lightweight because it is essentially dormant until activated by the user.