Silicon is not the best transistor material ever. For example, gallium arsenide can run at a switching frequency of 250 GHz thanks to faster electron velocity and higher electron mobility. https://en.wikipedia.org/wiki/Gallium_arsenide#GaAs_advantag...
Kenneth O. Stanley and Joel Lehman have a great book out on measuring novelty, and using it to search large parameter spaces for interesting behaviors.
Gavin argues that 1000x is possible. With the latest features of header-first syncing, and simultaneous multiple downloads of blocks, we're doing pretty well.