🎯 TL;DR

If you're allocating memory or creating objects repeatedly inside loops when the data doesn’t change—stop. Build once, reuse, and only clone when needed. This small change can lead to huge gains in performance, especially in high-frequency or large-scale systems.

🧠 The Principle: Avoid Repeated Allocations

Creating the same object(s) multiple times inside a loop causes:

  • Higher memory usage
  • Increased CPU cycles
  • More frequent garbage collection (GC)
  • Slower performance

Instead, build shared data structures once, and reuse or clone them only when needed.

📜 Real-Life Analogy: The Form Copying Example

Let’s say you’re filling out a form with mostly static data and need 10 copies.

  • ❌ Inefficient: You retype the entire form 10 times. Waste of time and energy.
  • ✅ Efficient: You fill out one master form and photocopy it 10 times. Fast and smart.

This is exactly how object creation in loops works in code. The CPU is your typist. Memory is your paper.

Before vs After: Code Comparison 

for (int i = 0; i < 10; i++)
{
    var data = new List
    {
        "sensor1",
        "sensor2",
        "sensor3"
    };

    Process(data);
}

- Above code Creates a new list each time.
- Allocates memory 10 times.
- Creates GC pressure.

Optimized Code (Allocate Once, Clone When Needed) 

var baseData = new List { "sensor1", "sensor2", "sensor3" };

for (int i = 0; i < 10; i++)
{
    var clonedData = new List(baseData); // shallow copy
    Process(clonedData);
}

- Above Creates the base list once.
- Clones it for each iteration to avoid shared references.
- Saves memory and CPU cycles.

The Concept: "Reduce Unnecessary Allocations"

❌ What's the problem?
If you're creating new objects inside a loop that don’t need to change every time, you’re doing unnecessary work. That leads to:

  • More memory allocations (objects on the heap).
  • More garbage collection.
  • More CPU cycles wasted rebuilding the same thing.

✅ The solution:
Build it once outside the loop if it’s static. Then, clone it inside the loop only if it needs to be modified per call to avoid shared reference issues

Key Takeaways Points

  • "If it doesn't change, don’t build it more than once."
  • Use analogies like form photocopying.
  • Show side-by-side code examples.
  • Explain how repeated allocations lead to higher GC frequency and slower execution.

🧩 Bonus Tip

Even in test code, performance matters—especially when tests run hundreds of times in CI/CD pipelines. Optimizing test code leads to faster pipelines and happier devs.