Senior C++ Engineer – High Performance Systems Oxford (Hybrid), £90k to £95k Avanti Recruitment is working with a deep-tech company behind a high-performance reasoning engine deployed on over 60 million devices worldwide. This is core engine development for an elite engineering team working on core C++ systems, where performance, correctness, and engineering quality are absolutely critical. The Role You’ll be working on a performance-critical C++ system, tackling problems around: \* Complex data processing and reasoning \* Concurrency and multithreaded systems \* Memory efficiency and low-level optimisation \* Cross-platform behaviour (Linux, Windows, macOS) \* System-level interactions where required This is hands-on, systems-level engineering. Skills required \* 10-15 years of software development experience \* Strong commercial experience with modern C++ (C++17 or later) \* Background in systems-level or performance-critical development \* Solid understanding of multithreading / concurrency \* Comfortable working close to the system (memory, OS behaviour, performance) \* Passion for writing high-quality, maintainable code Bonus points \* Experience with low-level optimisation \* High-performance backend systems \* Quant / trading systems \* Database or engine development \* Gaming / real-time systems \* Familiarity with cross-platform development What Makes This Role Different \* Work on a core product used at global scale \* Strong focus on engineering quality over shortcuts \* Backed by a major global technology organisation, offering stability and long-term growth If you’re a C++ engineer who enjoys working on complex, high-performance systems and wants to be part of something genuinely impactful, we’d love to hear from you