As far as I can tell, the slowness is with the network. The reason that PDX Bus crashes is that it is unresponsive while it accesses the network, and the iPhone OS thinks it has crashed and kills it.
I have a fix - the next version of PDX Bus has been significantly re-worked. It will have a whirly thing on the screen, a progress bar, and all network access is done in the background. This will not speed it up, but it will stop it from crashing.
Meanwhile - if it is very slow for you then try to access only one stop at a time, the new version of PDX Bus will be along very soon!