🤔 Common Myths That Don't Help
Performance optimization in C# is often misunderstood, leading developers to adopt practices that either have negligible impact or sometimes even hurt performance. Let's explore some common myths and learn what actually works.
1. 🔍 "LINQ is Always Clean and Fast Enough"
LINQ provides elegant and readable code, but it can introduce significant performance overhead. Each LINQ operation potentially creates intermediate collections and unnecessary iterations. While LINQ is excellent for development speed and maintainability, in performance-critical paths it can be a bottleneck.
2. 📏 "Always Pre-size Your Arrays"
Developers often believe that pre-sizing collections always improves performance. While pre-sizing can help when you know the exact size needed, arbitrarily choosing a large initial capacity can waste memory and potentially slow down your application. The built-in growth algorithms in collections like List are well-optimized for most scenarios.
3. 🏗️ "Structs Are Always Better for Performance"
While value types can improve performance by reducing heap allocations and garbage collection, using large structs can actually degrade performance. Every time a struct is passed as a parameter or assigned to a variable, its entire contents are copied. For larger objects, this copying overhead can exceed any benefits from avoiding heap allocation.
⚡ Real Performance Optimizations That Work
1. 🎯 Efficient Memory Management with Span
Span is like a superhero for memory operations! It provides zero-allocation access to memory and eliminates bounds checking in tight loops.
2. 🔑 Proper Value-Based Equality Implementation
Think of this as giving your objects a unique fingerprint. Good hash codes and equality implementations can make collections like Dictionary and HashSet blazing fast!
3. ♻️ Smart Array Pooling
Think of ArrayPool as a recycling center for arrays. Instead of creating new arrays all the time, we can reuse existing ones!
4. 📝 Optimized String Building
StringBuilderCache is like having a personal assistant for string operations. It keeps track of and reuses StringBuilder instances for you!
💡 Pro Tips
🚦 Don't optimize prematurely - profile first!
📏 Measure, don't guess
🎯 Focus on algorithms first, micro-optimizations last
🧪 Always test performance changes with real-world data
📚 Keep learning about new .NET performance features
There is a lot more that can be said and written about performance. In fact, there are books written on that subject but I wanted to share a few quick tips and share some of the common mistakes I have noticed people make. If I have gotten something wrong, please do correct me in the comments below. I always welcome cosntructive criticism, no one is perfect right! :)
Top comments (1)
Hardly. Most of the time this is a very strange way of seeing things, a heap allocation at least some times consists on a syscall (which is many times heavier than copying most structs) and it will put pressure into the GC (even if it is very minimal for the gen 0 or SOH).
You can easily remove the pressure of copying a large struct by passing them by-ref (which is, in fact, what most high performance libs do in .NET, for example they don't create a class for their matrices, they are structs and passed by ref). You also don't have the overhead of pointer indirection and the poor memory locality that comes with randomly allocating things on the heap. So while it is true that structs are not a silver bullet, they indeed are WAY better for performance than classes if you use them correctly (and I'm not overgeneralizing, almost every single piece of high performance application written in C# uses structs heavily for a fact).