CleanLink: Optimizing SQL Server Performance for Large Scale Payroll Processing on AWS

Overview

CleanLink is the UK’s leading provider of site management software, specializing in comprehensive solutions for the contract cleaning industry. Its flagship CleanLink Portal serves as a centralized hub for over 60,000 users, enabling real-time access to essential payroll, invoicing, and contract data. To ensure platform stability during high demand payroll periods, CleanLink partnered with Lambert Labs to optimize their Amazon RDS SQL Server database performance. By implementing Read Committed Snapshot Isolation (RCSI) and refining data processing logic, Lambert Labs eliminated critical database bottlenecks and lock contention, significantly improving reliability for end users during peak traffic.

Opportunity / Customer Challenge

CleanLink provides a leading SaaS platform that enables facilities management companies to streamline critical operations, including site management, invoicing, and payroll for tens of thousands of staff members. As their CleanLink Portal grew to serve over 60,000 users, the underlying data infrastructure, built on RDS, faced significant performance challenges during peak demand periods. Specifically, during monthly pay runs, the high volume of automated data processing clashed with thousands of concurrent user logins, leading to database CPU saturation and processing failures.

The primary challenge was to resolve these deep-seated database bottlenecks without disrupting the essential services that CleanLink’s customers rely on for accurate, timely payroll. The opportunity lay in conducting a technical deep dive into their AWS environment to identify the root causes of lock contention and resource exhaustion. By optimizing the existing RDS configuration and refining the data processing logic, Lambert Labs aimed to ensure that CleanLink’s platform could handle massive spikes in activity with enterprise-grade reliability, providing a stable foundation for the company’s ambitious plans to significantly increase their user base.

Solution

To address these scaling challenges, Lambert Labs conducted a technical sprint to enhance database observability. By analyzing Elastic Load Balancing Application Load Balancer logs with Amazon Athena and implementing RDS Performance Insights, we identified the primary bottleneck as lock contention, where background data processing was effectively blocking regular user access.

We resolved this by enabling Read Committed Snapshot Isolation (RCSI), allowing users to view data via versioned snapshots without interfering with active background updates. Additionally, the logic within the AWS Lambda functions responsible for processing payroll files was refined, breaking down large datasets into significantly smaller batches. This ensured that critical updates could complete reliably without triggering 15 minute execution timeouts or 5 minute database query limits during peak periods.

Finally, Lambert Labs provided a strategic roadmap for right-sizing the underlying AWS infrastructure. We advised transitioning from burstable instances to stable, production-grade servers to ensure consistent performance during high traffic pay runs and provide a reliable foundation for future user growth.

It was a very good experience working with Lambert Labs to review database performance and identify a number of solutions that have alleviated critical bottlenecks with our data processing. (James Stringer, Managing Director, CleanLink)

Outcome

The reliability of the CleanLink Portal was significantly improved during its most demanding operational periods. Following the implementation of Read Committed Snapshot Isolation (RCSI) and refined data processing logic, CleanLink successfully executed a high volume pay run with zero reported performance issues. The system maintained consistent stability, allowing thousands of concurrent users to access their files and accounts without the slowdowns or timeouts previously experienced during peak data processing. The platform is now capable of processing complex datasets simultaneously, ensuring that critical payroll tasks complete on time while providing a seamless experience for end users.

By identifying the root causes of lock contention and resource exhaustion, we provided CleanLink with the technical clarity needed to stabilize their platform. This project proves that targeted database tuning on AWS can unlock significant performance gains for high traffic environments without requiring a complex re-architecture. (George Lambert, CEO, Lambert Labs)

About CleanLink

CleanLink is the UK’s leading provider of site management software, specializing in comprehensive solutions for the contract cleaning industry. Its flagship CleanLink Portal serves as a centralized hub for over 60,000 users, enabling real-time access to essential payroll, invoicing, and contract data. By providing a scalable, cloud-based platform, CleanLink empowers organizations to automate complex administrative workflows and maintain high levels of operational efficiency across thousands of diverse client sites.