Considering that lifting the 1 mile 10 mph slow zone in Guelph saved just under 5 minutes, lifting the much shorter slow zone in Georgetown would save less than 5 minutes. Perhaps 3.
The report in question describes a 90 minute travel time for a stopping pattern which, according to my calculations
in an earlier post here, would take 107 minutes with the current (April 2021) tracks. So even with 4 minutes saved in Guelph starting December 2021 and 3 minutes saved in Georgetown at some point in the future, that still leaves about 10 minutes of travel time savings unaccounted for. For that amount of time they would need to find savings along the entire length of the route. Keep in mind that the longest station-to-station time is only 15 minutes to begin (Guelph to Acton).
My very rough ideas for where the 10 minutes of travel time savings may have been allocated:
5 min- Increase line speed from 70 mph to 90(?) mph west of Georgetown
2 min- Something with CN between Georgetown and Bramalea? Perhaps increase line speed from 60 mph to 70??
1 min- Organise track layout east of Bramalea to avoid the need for express trains to switch tracks (and thus slow to 45 mph)
2 min- Union Station Rail Corridor improvements enabling 45 mph operations all the way into the platforms.