C++ / Rust Systems Engineer (Ultra-Performance Systems)

Selby Jennings; Greater London; On-site; GBP 90,000 - 150,000; Full time

Job summary

Selby Jennings is seeking a technically ambitious engineer to design, build, and optimise high-performance, latency-critical systems. You will own features from design through production in a greenfield project within a small elite team.

The role spans from low-level systems and networking to algorithmic performance, with heavy emphasis on profiling, benchmarking, and clear architectural decisions in a fast-moving environment.

Qualifications

• 3+ years' experience building high-performance production systems.
• Proficiency in C++ or Rust.
• Deep understanding of memory, concurrency, networking.
• Experience with latency-sensitive or high-throughput systems.
• Strong problem-solving and ownership in ambiguous environments.

Responsibilities

• Design and develop high-performance, low-latency systems in C++ or Rust.
• Optimise systems for throughput, latency, and scalability.
• Work across the full lifecycle: architecture, implementation, testing, and production deployment.
• Analyse and improve system performance through profiling and benchmarking.
• Solve complex, non-obvious technical problems in a fast-paced environment.
• Collaborate in a small, high-calibre team with significant ownership and impact.

Skills

C++

Rust

Low-latency design

Profiling

Problem solving

Ownership mindset

Distributed systems

Education

CS/Math/Physics degree

Job description

We are working with a highly technical, fast-growing engineering team building latency-critical, high-throughput systems in a competitive and fast-moving environment. This is a greenfield opportunity within a small, elite team where engineers take full ownership of systems from design through to production.

The Role

You will design, build, and optimise high-performance systems where efficiency, scalability, and reliability are critical. The work is deeply technical and spans the full stack, from low-level systems and networking through to algorithmic performance and optimisation.

This is an environment where strong reasoning and problem-solving ability are just as important as systems experience. You will be expected to tackle ambiguous problems, make architectural decisions, and iterate quickly.

Key Responsibilities:

• Design and develop high-performance, low-latency systems in C++ or Rust
• Optimise systems for throughput, latency, and scalability
• Work across the full lifecycle: architecture, implementation, testing, and production deployment
• Analyse and improve system performance through profiling and benchmarking
• Solve complex, non-obvious technical problems in a fast-paced environment
• Collaborate in a small, high-calibre team with significant ownership and impact

Requirements:

• 3+ years' experience building high-performance production systems
• Strong proficiency in C++ or Rust (or willingness to transition to Rust)
• Deep understanding of systems concepts (memory, concurrency, networking, hardware interaction)
• Proven track record working on latency-sensitive or high-throughput systems
• Strong problem-solving ability and capacity to reason through complex, novel scenarios
• High ownership mindset with the ability to operate in an ambiguous, fast-changing environment

Preferred Background:

• Experience in high-performance domains such as trading systems, distributed systems, or large-scale infrastructure
• Background in competitive programming, advanced simulations, or complex algorithmic problem-solving
• Strong academic background in Computer Science, Mathematics, Physics, or a related field

Why This Role:

• Greenfield environment with significant influence over system design and direction
• Small, high-performing team with strong technical standards
• Fast iteration cycles and immediate impact of your work
• Opportunity to take full ownership of critical systems