Perception of speed is actually even more important than real speed most of the time, but assuming of course you've done all you could to improve real speed, here are the article's suggestions:
Progress bars: they look like they move faster if there are backwards-moving "ripples" in the bar.
2. If the progress bar is not going to move in a stable rate, have it pause near the beginning rather than at the end. If it speeds up movement at the end, users feel it's actually faster than it really is.
Radial progress indicators (which do not show how much time is remaining): make them "spin" faster.