It's currently about an hour and 15 minutes from Providence to South Station so it's closer to a 30 minute difference, which is big (https://www.mbta.com/schedules/CR-Providence/timetable?schedule_direction[direction_id]=1#direction-filter). In addition to the time savings, Electric Multiple Units are also much quieter and don't belch diesel exhaust into the communities they pass through. They're cheaper to maintain and far lighter than diesel electric locomotives too which puts a lot less stress on the rails and ballast.