Change rounding thresholds

This pull request changes values displayed on the Performance Platform, eg 0.84m is now 842k. This can/will affect all the numbers we display.

I'd like to have a conversation with whoever is interested about how we display data, specifically whether we should show data to a certain number of significant figures, whether we should pad with zeros and what assertions that means we're making about the data. I'm on 2nd line until the 8th of January but I've made a note to have a chat then.