5 Simple C++ Performance Tips That Make a Big Difference

C++ is known for its speed, but small inefficiencies can add up fast. Here are 5 simple techniques you can start applying today to make your C++ code faster and cleaner.

✅ 1️⃣ Prefer ++i Over i++ in Loops

In most cases, especially with iterators, ++i is faster because it avoids creating a copy of the original value. This reduces overhead in tight loops.

✅ 2️⃣ Pre-allocate Memory with reserve

When you know how many elements you’ll store, pre-allocate space to avoid costly reallocations:

std::vector<int> data;
data.reserve(1000);  // Prevents multiple dynamic allocations

✅ 3️⃣ Use emplace_back Instead of push_back

emplace_back constructs elements in place, saving unnecessary moves or copies:

std::vector<std::string> v;
v.reserve(3);
v.emplace_back("one");
v.emplace_back("two");
v.emplace_back("three");

✅ 4️⃣ Minimize Virtual Function Calls

Use virtual functions only where polymorphism is truly needed. Virtual calls add indirection and prevent inlining, which can slow down hot code paths.

✅ 5️⃣ Leverage constexpr and inline

Let the compiler do more at compile-time and reduce runtime cost:

constexpr int square(int x) { return x * x; }

🎯 Final Thoughts

By applying these small tips, you’ll write C++ code that runs faster without major rewrites. Stay tuned for more deep-dive performance posts!