Eddi: Just a FYI: You replied directly to me. Didn't want to repost it here without your knowledge, in case you didn't want it posted here (I'm replying from the Google Group).
Here's something to try: I know it's painfully slow, but try printing everything at 5mm/s: loops, sparse infill, and solid infill; let us know if that fixes it. If it does, that may mean that you're running into a similar problem I'm having: the speed change from perimeter->infill requires an increased filament pressure, a problem that's particularly exacerbated by bowden setups (mine). It looks like you're going from 6.4mm/s-->48mm/s, which is a huge increase that the pressure may not be able to keep up with. Here's an example of optimal pressure changes (left) and standard speed changes (right), as mentioned in [1]:
And that's only for a 20% increase in speed, much lower than your 700%. For more info, see [2, 3]
References: