PDF text-rendering on an iPad has performance issues. Meanwhile, Instapaper, Reeder, Flipboard, other news reading applications, and even the new version of iBooks, work very well on all iPads.
So the argument that iPads don’t handle PDFs well, which is why iPad magazines get published as a series of PNG images, feels very shallow. If that’s the case then maybe the problem isn’t with the hardware. Maybe the problem is with PDFs.