Be Careful with Multiple Enumerations

Enumerating the same LINQ query multiple times can lead to performance issues. Store the results in a list if you need to use them multiple times:

// Bad: Enumerates twice
var count = query.Count();
var firstItem = query.FirstOrDefault();

// Good: Enumerates once
var results = query.ToList();
var count = results.Count;
var firstItem = results.FirstOrDefault();