Use indexer instead of linq (ARCH607)

Key dotnet.performance.use-indexer-instead-of-linq · Severity info · Category performance

Accessing the first or last element of a list via First()/Last() adds iterator overhead; the indexer is O(1).

Incorrect

var firstItem = list.First();
var lastItem = list.Last();

Correct

var firstItem = list[0];
var lastItem = list[^1];

Fix

Use [0] or [^1] on indexable collections.