I would suggest GBP/NZD, GBP/AUD, GBP/CAD, and GBP/JPY are the pairs with the highest volatility and CAD/CHF, EUR/CHF, AUD/CHF and CHF/JPY has been the less volatility Forex pairs among the cross rates as far as I am aware.
I trade from Austria using an ASIC broker FP Markets and to me, I find EURUSD to be the fastest because I can see that it is highly volatile and CHFJPY the slowest in the forex markets.
Certainly there will be more profit with currency pairs but in applying rapid movement we need scalping techniques and very high accuracy to avoid mistakes that can result in losses.
The fastest pairs in forex, in my opinion, have always been EURUSD and the slowest CAD/CHF, EUR/CHF, AUD/CHF have been the less volatile Forex pairs among the cross rates.