innsertnamehere
Superstar
Metrolinx has been working to address that one for what seems like a decade. I believe the plan is to upgrade the switches to 45mph switches as Dan mentioned though.. which while not 75mph like @reaperexpress has mentioned, is a significant improvement on the existing switches which I'm guessing operate at around 10mph.The place where we need this most is Union station. Trains crawl through that mess of track.
But I think the speed restrictions are because of the archaic signaling system
Last I heard the switch installation in the USRC is complete, and once the signaling upgrades are done track speeds can improve significantly. I don't think that is scheduled until late 2021 or early 2022 though.