CppCon 2026

In modern C++, std::unordered_map is the de facto #2 container. Its dominance signifies a fundamental shift in application design: the performance-critical need for O(1) average-case key-value lookups.

Join as we move beyond "just use a hash map" and explore the critical, real-world implications of this choice. We'll start by benchmarking the classic std::map (red-black tree) against std::unordered_map (hash table) to understand exactly what you gain-and what you might lose.

However this power comes with risks. An average-case O(1) can quickly degrade to a catastrophic O(n) without warning. We will profile and dissect the actual costs of using a hash map:

• The Hash: What makes a good hash function? We'll go beyond std::hash and see how to write effective, fast hashers.
• The Collision: How do different collision-handling strategies impact performance and memory?
• The Re-hash: What is "load factor," and when does the hidden cost of a full table re-hash destroy your performance gains?

We'll conclude with a practical decision-making framework for when to choose std::unordered_map , when to fall back on the ordered std::map , and how std::string -the container we often forget is a container-fits into this modern landscape.

You will leave this session knowing precisely which data structure to deploy for maximum performance.

This talk presents some design choices, compromises, and optimisations of the implementations of std::flat map and std::flat set. It will cover a brief design history of the original paper regarding the class layout, libc++'s best effort to provide strong exception guarantee on those containers, compromise on the iterator choices between SCARY and more strongly typed, some optimisations on various operations and some tips about avoiding running some issues with these containers.

According to VGInsights, about 10% of games released on Steam in 2024 used a custom engine, but those games represent 41% of units sold. Most "how an engine works" talks come from the AAA end of that distribution. This one comes from the other end of that distribution: a teaching-scale engine, where every system has to be small enough to understand from first principles. The problems are the same as in a big engine, but the smaller surface is what makes the architecture legible.

In this talk, we'll walk the spine of the engine in modern C++: allocators and handles in the core, the job system, the graphics abstraction question, the asset pipeline split between pipeline-time and runtime, and scene representation including ECS. We finish on serialization, where C++26 reflection (P2996) offers a path past today's reliance on macros and external code generators.

Modern storage hardware has evolved at a breakneck pace. PCIe Gen 5 NVMe drives can push data at 10 GB/s, yet standard C++ file abstractions often leave them starving for data. Many developers think they need to abandon portability in favor of unmaintainable, OS-specific kernel bypasses to achieve the throughput necessary to saturate these drives. This session is for developers writing high-throughput, performance-critical applications who want to hit bare-metal speeds without sacrificing clean architecture, cross-platform support, or type safety.

Using a high-throughput cryptographic hashing engine as a concrete case study, this presentation demonstrates how to design a hardware-saturating data pipeline built entirely on the idioms of C++26. We will explore how the mathematical design of an algorithm - specifically BLAKE3's binary Merkle tree structure - can be mapped directly to wide SIMD vector lanes and concurrent CPU cores. We will walk through an execution model that completely bypasses the OS page cache, orchestrates memory without heap allocations on the hot path, and unifies OS kernel quirks in a portable way.

By the end of this presentation, you will learn how to replace rigid thread pools with lock-free, asynchronous execution graphs using Sender/Receiver paradigms (std::execution) and vectorization (std::simd). Crucially, we will focus on the build engineering required to make this work today. We will cover how to use advanced CMake tooling to safely compile multi-architecture vector binaries from a single source of truth, how to prevent LTO cross-contamination, and how to structure your pipeline today to seamlessly absorb upcoming C++ features in a world of trailing vendor toolchains.