[igouy]

>> Edit: This Quora question mentions the performance of Swift before and after unsafe programs were included

That Quora answer makes claims which are not true.

The Swift benchmarks game programs were always compiled with -Ounchecked (since Dec 7 2015).

The before was naive transliterations (from other programming languages) of single-core programs -- just to demonstrate that Swift was installed.

The after was someone doing the work and contributing programs written for Swift and written for multi-core.