All the iPhones which run the new iOS 7 were tested for their speed. Boot-up times and Temple run were utilized as benchmarks. Evidently so, a simple pattern emerged with the iPhone 4 being the slowest and the iPhone 5S being the fastest of the lot.

iPhones Speed Comparison

For a quick specification comparison :

iPhone 4iPhone 4siPhone 5iPhone 5ciPhone 5s

You will see that the slowest by hardware aswell as benchmarks is the iPhone 4. It is quite amazing that Apple still supports the iPhone 4 which was released back in 2010 June. Here are the results :

Boot Up Time

iPhone 5S: 24 seconds to boot up

iPhone 5C: +3 seconds more than the iPhone 5S

iPhone 5: +3 seconds more than the iPhone 5C

iPhone 4S: +1 seconds more than the iPhone 5

iPhone 4: +13 seconds more than the iPhone 4S

Opening Temple Run 2

iPhone 5S: 5 seconds to open the game

iPhone 5C: +3 seconds more than the iPhone 5S

iPhone 5: +0 seconds more than the iPhone 5C

iPhone 4S: +6 seconds more than the iPhone 5

iPhone 4: +14 seconds more than the iPhone 4S

Browser speed

Opening "www.theunlockr.com".

iPhone 5S: 5 seconds to load the site

iPhone 5C: +0 seconds more than the iPhone 5S

iPhone 5: +1 seconds more than the iPhone 5C

iPhone 4S: +3 seconds more than the iPhone 5

iPhone 4: +12 seconds more than the iPhone 4S

The iPhones other than iPhone 4 seem to be performing pretty well, with relatively smaller distribution of scores. The Aging iPhone 4 with a single core CPU simply cannot keep up with the rest. Still Pretty good scores.

Source