Should I update my iPhone 4 to iOS 7?

I'm just wondering if my iPhone will be able to handle the new update. Will it be any laggier or slower? It's currently on iOS 6.1.3 and it can be a tad bit laggy at times already. Has anyone who has updated with an iPhone 4 experienced any issues?

Added (1). I'm well aware of the release date and the amount of traffic Apple will have on their servers due to all the people downloading iOS 7. I want to know if downloading iOS 7 on my iPhone 4 will cause it to be slower, not if I should download it on the release date, which by the way is today.

IOS 7 is available on September 18 for the iPhone 5, 4S and 4 as a free update.

Wait a day or two before downloading iOS 7.

Everyone will be downloading it on the 18th and Apple's servers might be too busy.