IconBeFast is a good patch, but it only helps icons load faster. The speed problem with picture.datatype is obvious when you use applications that load in lots of bitmap images, like YAM for example, or dock/start bar programs that need to load several small bitmap images. This isn't something I made up, I've experimented with 3.1, 3.9 and a hybrid 3.1/3.9 system, and in the end the main culprit for the speed problem is picture.datatype. The more images a 3.9 system has to load, the slower it will look compared to a 3.1 system. If your system is pretty default, and you don't use VisualPrefs (with bitmaps), Birdie, MUI with patterns or modern applications that use datatypes to load skins and GUI elements, you probably wouldn't notice the difference. But when you use an A1200 as your main system every day, waiting twice as long for things to load when you know it's capable of loading them much faster with an older datatype can get annoying. It's the reason I switched back to 3.1 from 3.9, 3.1 was just much snappier for the kind of usage I wanted to get from my Amiga.