Recently I updated the Microsoft Weather app to take advantage of new Windows Phone 7.5 features like background agents, secondary tiles, and FAS. The update hit the Marketplace today.
In addition to having new features, this version was architected from the ground up for performance following many of the guidelines I call out in my recent blog post Optimizing Apps for Lower Cost Devices.
I encourage you to follow the same performance/UX principles demonstrated by this new Weather update. Following these principles will ensure your apps perform great regardless of the device.
Hope you like the new update and have fun building for Windows Phone!