3 LINQ Mistakes That Hurt Backend API Performance in .NET

LINQ looks clean and harmless in C#. But in real backend APIs, small mistakes can quietly turn into serious performance issues. Here are 3 I’ve seen (and made) while working with .NET and Entity Framework: 1. Loading entire tables into memory A common mistake is doing this: var orders = dbContext.Orders.ToList(); var recent = orders.Where(o => o.CreatedAt > DateTime.UtcNow.AddDays(-7)); This pulls everything into memory first, then filters in C#. The problem: unnecessary memory usage slow proces