Nice link from The Loop to an Ars Technica article where they tested the iPhone 4 running iOS 6.1.3, iOS 7.0 and now iOS 7.1 that was released as an over-the-air update yesterday. iOS 7.0 really slowed down the — almost 4 year old — iPhone 4 when it shipped in the fall. It looks like iOS 7.1 makes your iPhone 4 faster across the board than iOS 7.0, but still slightly slower than iOS 6.1.3 (the last build before iOS 7.0 was released).

If you're still running iOS 6.1.3, then it's up to you if you want to stick with it, but it looks like this is the first version of iOS 7 that is almost as fast and also brings some of the new iOS 7 features, look and feel.