NET Performance Engineer

Initialize Ltd

Charing Cross, United Kingdom

5 days ago

Role details

Contract type

Permanent contract

Employment type

Full-time (> 32 hours)

Working hours

Regular working hours

Languages

English

Experience level

Intermediate

Remote

Charing Cross, United Kingdom

Query Performance

.NET

Adobe InDesign

Artificial Intelligence

Batch Processing

C Sharp (Programming Language)

Code Review

Databases

Language Integrated Query

Memory Management

Load Testing

Microsoft Visual Studio

Memory Leaks

SQL Databases

Diagnostic Tools

DotTrace

GPT

Data Pipelines

Profile, diagnose, and resolve performance bottlenecks across .NET services - from GC pressure and memory leaks to thread contention and I/O saturation
Own memory management strategy across long-running services - heap allocation patterns, LOH fragmentation, finaliser queues, and GC tuning (gen0/1/2, server vs. Workstation, DATAS)
Investigate and optimise high-throughput data pipelines - batch processing, streaming patterns, buffer management, and backpressure handling
Identify and resolve large dataset query performance issues - index utilisation, query plan analysis, pagination strategies, and aggregation efficiency across both relational and document databases
Establish and maintain performance benchmarking infrastructure using BenchmarkDotNet and load testing tooling - define baselines, track regressions, and gate releases on performance criteria
Conduct performance-focused code reviews - identify allocations, boxing, closure captures, LINQ misuse, and other common .NET performance anti-patterns
Collaborate with product engineers to surface performance constraints early in design, without blocking feature delivery
Produce clear diagnostics and findings documentation that non-specialists can act on

AI development experience - usage of AI tools (Claude, CoPilot, ChatGPT) - highly desirable
4-5+ years of .NET/C# development with a demonstrable specialism in performance engineering
Deep, hands-on experience with .NET profiling tools - dotMemory, dotTrace, PerfView, Visual Studio Diagnostic Tools, or equivalent
Strong understanding of .NET memory management internals - GC generations, LOH, pinned objects, finalisation, and how allocation patterns affect runtime behaviour
Experience optimising high-throughput data processing pipelines - including async/await patterns, Channel, pipelines, and avoiding synchronisation bottlenecks
Proven ability to diagnose large dataset query performance issues across both relational (SQL) and document databases, including index analysis and query plan interpretation
Familiarity with ETW, EventPipe, and diagnostics tooling (dotnet-trace, dotnet-counters, dotnet-dump)