In the How fast is your phone? thread we tested two apps that are native on the Pre, EVO, Epic, Droid X, BlackBerry Torch, Storm, and Bold: Facebook and Google Maps.
Everyone else was faster than even a rooted Pre overclocked to 1 GHz.
By a lot.
The reason is that the webOS concept is to make apps like web pages that your phone will re-interpret each time the app is opened. The phone then turns the Java and HTML/CSS into usable machine code on the fly. webOS is like giving the phone the ingredients for a half-baked cake and having it bake the cake every time you open the app. If you look at a webOS app, you can see most of code.
Unfortunately this makes it pretty easy for someone to take your code. For instance, a 7-day trial program can be changed to seventy years. These inherent limitations are reasons some developers say is why they will not release their programs on webOS.
Other platforms let a developer "compile" their program into machine code that can be tweaked and optimized. So you don't have to bake the cake each time each time you open an app. The developer can then optimize the final code putting the icing on the cake.
That is how a 2009 BlackBerry with just as slow a processor can be four times as fast as a Pre.
More memory will help too but in the end the other phones will, by their design, be faster at the same processor speeds. That is the different between interpreted and compiled code.