West Croydon trains get 3 minutes recovery time at Dalston Junction. This might explain slow running. The line speed on the East London line is 40 mph.. The crossover east of Highbury is 30 mph for trains leaving from platform 1. Also the signal for southbound east London line trains arriving into platform 4 is held at danger so neccistates a cautious approach. Unlike the tube there are TPWS overspeed loops set at 10 mph on the approach to all signals. After clearing Dalston Junction the limit is 40 mph as far AA the Hollywell curve, then it's basically 40 all the way to Wapping and 30 through the Thames tunnel past Rotherhithe and through to Surrey Quays. 40 after that except for a brief 30 through Canal Junction.

Unfortunately there's lots of timetable padding south of New Cross Gate towards Croydon where the line speed is 60 until Norwood Junction. Nevertheless a determined driver can reach at least over 50 even between stations quite close together thanks to the installed power on a 378. 55 is possible between Forest Hill and Sydenham for example.