Performance
-----------
-* [During type unification, the complexity of comparing variables for
- equivalance was reduced from `O(n!)` to `O(n)`][1.9tu]. This leads
- to major compile-time improvements in some scenarios.
+* [The time complexity of comparing variables for equivalence during type
+ unification is reduced from _O_(_n_!) to _O_(_n_)][1.9tu]. This leads
+ to major compilation time improvement in some scenarios.
* [`ToString` is specialized for `str`, giving it the same performance
as `to_owned`][1.9ts].
* [Spawning processes with `Command::output` no longer creates extra