Lead Engineer (Performance and Reliability) in London

About Us

Bauer Media Outdoor is reshaping Out-of-Home advertising across Europe. Our network spans thousands of DOOH screens, data-driven delivery systems, and enterprise platforms that power scheduling, booking, content delivery, and performance reporting at scale. We are in the middle of a modernisation programme with new products, new infrastructure, and a reinforced engineering discipline. You will be part of a team raising the bar on reliability, observability, and non-functional excellence across our platforms.

The Role

You will be the technical lead for non-functional requirements across one of our most critical internal platforms. The system will ultimately be handling over €1 billion of revenue, supporting millions of transactions a day, enabling both internal and external customers, hence needs to do this without degrading performance or stability.

Your remit covers performance front end and back end engineering, architecture and design, reliability, resilience, observability, and capacity planning. Much of our estate runs on AWS, so you will bring strong cloud awareness and understand how architectural choices influence throughput, latency, cost, and scaling behaviour. This is hands-on work. You will define the NFRs, test them, break them, and enforce them, as well as working with architects and other lead engineers on ensuring architectures and designs meet these requirements.

Key Responsibilities

• Performance, Scalability & NFR Definition
  • Define, document, and own non-functional requirements across areas such as performance, availability, reliability, scalability, observability, cost and security constraints.
  • Build and execute performance, load, stress, concurrency, and soak tests shaped by the NFRs you set.
  • Establish SLOs, SLAs, and SLIs that reflect real user demand and business outcomes.
  • Model expected load and determine capacity baselines.
  • Translate business workflows into measurable system behaviours: throughput, response time, peak concurrency, degradation thresholds.
• Quality Engineering & Observability
  • Implement qualitative and quantitative testing patterns that validate each NFR.
  • Strengthen observability using AWS CloudWatch, X-Ray, metrics, logs, distributed tracing, and event correlation.
  • Define what “healthy” means for the platform and establish mechanisms to detect and predict deviation.
• Cloud, Architecture & Collaboration
  • Influence architectural decisions and designs using evidence from performance modelling and NFR constraints including inputting into UX and front end design to align the customer experience with the reality of the product.
  • Validate AWS scaling policies, resource limits, timeouts, and data access patterns.
  • Provide clear, data-backed recommendations that highlight trade-offs between cost, performance, and reliability.

What We’re Looking For

• Expertise in full stack engineering, performance engineering, non-functional testing, and reliability engineering.
• Strong understanding of NFR categories: performance, availability, reliability, resilience, capacity, security constraints, operability, cost and maintainability.
• Solid knowledge of AWS architecture and how NFRs translate into cloud scaling behaviour, resource use, and service limits.
• Hands-on experience with performance tools: JMeter, Gatling, Locust, k6, or similar.
• Ability to diagnose bottlenecks across user experience, front end, application logic, APIs, databases, cloud infrastructure, and distributed systems.
• Someone who challenges assumptions early, brings evidence, and insists on technical rigour.
• Related environment maintenance, awareness and impact outcomes.

What Success Looks Like

• 3 Months
  • NFRs are fully defined, documented, and agreed across engineering, product, and architecture.
  • Performance baselines, SLOs, and capacity thresholds exist for all key workflows.
  • Early bottlenecks across the AWS estate and application layers are identified with evidence.
  • Initial performance test coverage and observability improvements are underway.
• 6 Months
  • A stable, automated NFR validation framework is integrated into CI/CD pipelines.
  • The platform handles expected load with predictable resource usage and minimal degradation.
  • Dashboards expose real-time performance, concurrency behaviour, and NFR compliance.
  • Engineers and product teams regularly use your insights to make architectural choices.
• 12 Months
  • The system consistently meets or exceeds all core NFRs under real and peak load.
  • Performance testing, resilience testing, and observability practices are fully embedded into delivery.
  • AWS scaling behaviour is tuned, predictable, and cost-efficient.
  • The platform supports 300+ concurrent users and multi-process workloads without instability.
  • You are recognised internally as the authority on system performance, reliability, and non-functional rigour.