[saagarjha]

Swift’s slowness is kind of unfortunate, although I hear that there is work being gone to remove a lot of the lifetime cruft that was going in behind the scenes to make it slow. And unfortunately I think the primary motivation for Swift’s performance is driven by its primary application, which is UI development, so “good enough” performance usually works…

[pjmlp]

WWDC has a couple of talks regarding runtime improvements, and low level coding including unsafe style coding with Swift.