Update comment

Author: Matt Zanchelli

Tests/SwiftAlgorithmsTests/TestUtilities.swift

@@ -107,9 +107,9 @@ func XCTAssertUnorderedEqualSequences<S1: Sequence, S2: Sequence>(
       missing.append(elt)
       continue
     }
-    // Since ordering does not matter, this is a small
-    // optmization that avoid removing a index in the middle
-    // of the array and having to slide all elements.
+    // Since ordering does not matter, avoid the performance costs of removing
+    // an element at an index in the middle of the array, which requires
+    // shifting all subsequent elements down.
     let lastIdx = s1.index(before: s1.endIndex)
     if lastIdx != idx {
       s1.swapAt(idx, lastIdx)