ImageOptim Case Study
ImageOptim could have reduced the size of Tweetbot’s images from 26 MB to 9 MB (via Dan Wood):
Although Xcode optimisation is assumed to improve decoding speed of PNG images, testing on an actual device disproves that […] Xcode-optimized images were significantly slower to display. Decoding speed appears to be correlated to image file size more than anything else (most likely savings on byteswapping are negligible compared to additional disk I/O and extra data to decompress.)
