As posted in the thread I linked, about the fastest ever Reading service was the xx00 from Waterloo in the timetable around 1989.
Waterloo dep xx00, Clapham Junction xx07, Richmond xx15, Ascot xx39, Martins Heron xx44, Bracknell xx48, Wokingham xx54, Winnersh xx58, Winnersh Triangle xx00, Earley xx02, Reading xx07.
Given that is 67 minutes for 44 miles and it cuts out loads of stops, the trains might as well stop where the custom is and take 80 minutes like they do today. There was an xx03 which went to the Bagshot line, with a Reading connection at Ascot, and a slower xx33 to Reading calling with the following pattern.
Waterloo dep xx33, Clapham Junction xx40, Richmond xx48, Feltham xx56, Staines xx02, Egham xx06, Virginia Water xx10, Sunningdale xx16, Ascot xx20, Martins Heron xx24, Bracknell xx28, Wokingham xx34, Winnersh xx38, Winnersh Triangle xx40, Earley xx42, Reading xx47.
However, at that time, the departures from Waterloo to the Windsor Lines were xx00 Reading fast, xx03 Guildford via Aldershot, xx13 Windsor, xx15 Kingston loop, xx25 Weybridge via Hounslow, xx33 Reading slow, xx43 Windsor, xx45 Kingston loop, xx55 Weybridge via Hounslow.
The off-peak Reading service from 1997 to 2003 was
xx07/xx37 from Waterloo - Vauxhall, Clapham Junction, Putney, Hounslow, Feltham, Ashford, Staines, Egham, Sunningdale, Ascot, Martins Heron, Bracknell, Wokingham, Reading
xx22/xx52 from Waterloo - Clapham Junction, Richmond, Twickenham, Feltham, Staines, Egham, Virginia Water, Sunningdale, Ascot, Martins Heron, Bracknell, Wokingham, Winnersh, Winnersh Triangle, Earley, Reading.
The xx07/xx37 later gained a Brentford stop and was diverted after Egham to Weybridge, to replace the Staines to Weybridge shuttle. The journey at the London end was sufficiently slow that there was only a six minute gap between the services all the way from Staines to Wokingham.