Software Senior Architect Lead

Location: Poland (hybrid)

Are you curious, motivated, and forward-thinking? At FIS, you'll have the opportunity to work on some of the most challenging and relevant issues in financial services and technology. Our talented people empower us, and we believe in being part of a team that is open, collaborative, entrepreneurial, passionate and above all fun.

About The Team: You will be joining FIS' Non-Functional Engineering (NFE) team, the group accountable for the performance, scalability and resilience of the OPF payments product line. Operating globally across EMEA, the US, APAC and India, we define and validate the non-functional requirements behind mission-critical payment platforms, engineer the load, stress and endurance testing that proves them, and translate measured evidence into tuning, sizing and architecture decisions. Our purpose is straightforward: ensure FIS products are fast, predictable and resilient at real production scale, long before a customer ever feels a bottleneck.

What You Will Be Doing: As a Software Architect, you will own the deep technical analysis that explains how our payment platforms behave under load and, more importantly, how to make them significantly faster. You will profile running systems, dissect their runtime behaviour and challenge design decisions, working shoulder to shoulder with the engineers who build the product. You will not simply report findings; you will prototype, measure and prove the optimisations that turn them into quantifiable gains in throughput, latency and cost. This role will suit someone with a developer mindset, who enjoys reading code as much as reading metrics.

• Profiling Java applications end to end across CPU, memory, threads and I/O, using tools such as Java Flight Recorder, async-profiler and JProfiler, to isolate the hot paths that constrain throughput.
• Analysing thread dumps to diagnose lock contention, deadlocks, thread-pool exhaustion and blocking I/O, then reshaping the concurrency model to remove the constraint.
• Owning garbage collection analysis and JVM tuning, sizing heaps, selecting and configuring collectors and reducing allocation pressure, to cut pause times and stabilise latency under sustained load.
• Reading and interpreting database execution plans to tune expensive SQL, correct indexing and join strategies, and resolve contention and locking at the data layer.
• Working directly in the codebase alongside development teams to propose, implement and validate code-level optimisations, and embed performance thinking into design reviews, coding standards and delivery pipelines.
• Designing and leading load, stress, soak and failover campaigns, and driving performance investigations during customer escalations, converting every finding into a permanent fix, a sizing recommendation or a new predictive test.

What You Bring: Substantial experience as a performance architect or senior performance engineer, optimising large-scale, high-throughput Java systems running in production. Deep, hands-on expertise in Java profiling (Java Flight Recorder, async-profiler, JProfiler or YourKit) to isolate CPU, memory, lock and I/O bottlenecks. Proven ability to analyse thread dumps and reason rigorously about concurrency, identifying deadlocks, contention and thread starvation and prescribing the fix. Strong command of JVM garbage collection internals (G1, ZGC, Shenandoah, CMS), with real experience interpreting GC logs and tuning heap sizing and allocation behaviour. Confidence reading database execution plans (Oracle or PostgreSQL) and tuning SQL, indexes and schema design to eliminate data-layer bottlenecks. A developer mindset: you are at home in the codebase, read and write production-quality Java, and would rather prove an optimisation by building and measuring it than by describing it.

What We Offer You: Opportunities to make an impact in fintech, personal and professional learning, inclusive, diverse work environment, resources to give back to your community, competitive salary and benefits.