AgileSource are looking for 4 - 5 Senior Performance Testers on a Permanent basis. This role will require 1 day a week in the office (London or Newcastle). Role Summary An experienced Performance Test Specialist is required to plan and deliver performance validation activities across complex digital platforms and core Back End systems. The role focuses on practical implementation within structured delivery environments where system stability, throughput, and scalability are essential. This position is delivery-oriented and requires strong technical capability in modern cloud-based and distributed architectures. Core Responsibilities Develop and implement performance test strategies including load, stress, endurance, capacity, and scalability testing Evaluate test outcomes, application logs, and infrastructure metrics to identify performance constraints Define and confirm non-functional performance requirements, workload models, and capacity estimates Create and maintain automated performance scripts and supporting documentation Conduct testing within cloud-hosted non-production environments Document and report performance issues with supporting technical evidence Integrate performance testing activities within automated build and deployment pipelines where applicable Produce performance reports and contribute to defect review discussions Collaborate with engineering, architecture, infrastructure, and operations stakeholders Required Experience andamp; Skil