Most of the pilots at Ryanair follow the SOPs and I do not know of anyone who intentionally does not follow them. The Boeing 737 Flight Crew Training Manual allows as to to maintain speeds upto 30 Knots. :
737NG Flight Crew Training Manual Chapter 2 page 2.5
"....."Normal taxi speed is approximately 20 Knots, adjusted for conditions. On long straight taxi routes speeds up to 30 knots are acceptable, however at speeds greater than 20 knots use rudder pedal steering only..."
I personally do not taxi that fast, but there have been times at Stansted when ATC has requested me to increse speed during taxi, especially for Runway 05. If someone is landing at that time and has not been on ground frequency they will say surely, look at Ryanair taxiing fast again.
I assure you that the company does provide us and requires to obey the speed limits, max 10 knots in the approns, max 20 knots between the terminals and the fire station, and to this day I do not know of anyone in Stansted been reported for fast taxiing, or in that matter for unsafe or un-comfortable opperations.