•6 min read
Measuring the Impact of Engineering Work
How I measured SDK performance improvements at Rokt, starting with the customer experience, and turned the experiment setup and analysis into two reusable Claude Skills.
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Hi, I'm Cris Ryan Tan
Senior Full-stack Engineer specializing in web performance optimization and AI-assisted development. I build high-performance applications and leverage AI to accelerate engineering productivity.
10+
Years building for the web
50%
Faster CI pipelines
75%
Cold-load reduction
68%
Faster SSR page loads
About Me
Innovative and detail-oriented Senior Software Engineer with a specialisation in Frontend technologies and deep expertise designing and developing high-performance, scalable web applications.
Expert in modern JavaScript frameworks, with a strong focus on creating intuitive, responsive, and accessible user interfaces. Sound experience in backend development, DevOps projects, and end-to- end testing.
Passionate about web performance optimization, AI-assisted development workflows, and staying current with emerging technologies. I write about cutting load times, building AI coding agents, and turning engineering expertise into scalable team capabilities.
As the co-founder of Blitzstack.io, I'm dedicated to empowering developers with tools that accelerate development and improve code quality.
Programming Languages
- JavaScript (ES6+)
- TypeScript
- C#
Frontend Technologies
- React.js, Next.js, Remix
- Tailwind CSS, React Router
- Angular, Vue.js
State Management
- Redux
- RxJS
Backend
- Node.js, tRPC
- Prisma, PostgreSQL
- .NET (.NET Core / ASP.NET)
Testing & Tools
- Jest, Vitest, Playwright
- Contract Testing (Pact)
- Webpack, Rollup, Storybook
DevOps & Performance
- Buildkite, CircleCI, Nx, Bun
- Lazy Loading, Code Splitting
- Tree Shaking, Caching
Observability & Experimentation
- Datadog Monitors & Runbooks
- A/B Design & Analysis
- SQL, Trino Analytics
AI-Assisted Development
- AI Coding Agents & Workflows
- Claude Skills & Prompt Engineering
Experience
Senior Software Engineer
Rokt - New York, USA
- Cut SDK time to interactive by 11% at p50 and 12% at p95. Modelled at a 0.3-1.9% revenue lift depending on percentile.
- Moved the web SDK's offer-selection path onto the platform's new backend architecture, ramping partner by partner behind routing controls with parity checks and per-partner monitoring at each step, so any revenue impact stayed visible and reversible.
- Introduced contract testing (Pact) to de-risk that migration, growing it from a single-repo experiment into shared infrastructure across all three SDK consumers (web, iOS, Android), the transactions provider, and the server-to-server surface, so client and server drift surfaces at review time rather than after release.
- Modernised the web SDK's build and CI by consolidating on Nx with affected-only scoping, sharding the PR pipeline, migrating npm to bun, and surfacing bundle size per PR. Cut PR build time by ~45% and mainline by ~33%, roughly halving what the team waits on for every change.
- Rebuilt the on-call surface ahead of new engineers joining the rotation. Introduced a diagnose-alerts skill to help engineers diagnose SDK issues.
- Acted as the SDK technical expert during partner onboarding, fielding integration questions and clearing blockers for partners including Cinemark, eBay, and Kroger.
- Invested in team leverage: guardrails for AI-generated code and performance guidelines in
AGENTS.mdthat keep render-latency regressions from reaching partner pages, plus reusable playbooks for pitching and code review.
Senior Software Engineer
Lorikeet - Sydney, Australia
- Shipped Concierge, rebuilding Brands into Concierges as the hub for multi-channel CX config. Standardized channel-level settings as the single source of truth, aligned with a DB migration and large backfills to cut duplication and make multi-env changes safer.
- Shipped Coach, an AI agent that explains metric shifts, diagnoses root causes, and recommends fixes, turning reporting data into actionable insights.
- Built partner reporting for Quality Score, CSAT, and containment rate, giving partners visibility into key CX metrics across their support operations.
- Optimized SSR performance in React/Remix by instrumenting loaders with performance markers, identifying bottleneck queries, and applying parallel execution and deferred streaming patterns. Cut average page load time from 2.2s to ~700ms (~68% reduction).
- Audited the full infrastructure stack for compression and bundle size gaps. Enabled Brotli on Cloud CDN, reducing web app cold load transfer by 75% (1.56 MB to 392 KB). Reduced chat bundle size by ~630 KB through tree-shaking, eliminating 87% of one chunk.
- Built a preparative iframe preloading mechanism for the embeddable chat widget, achieving an 85% cache hit rate and cutting widget time-to-ready from 1.24s to 681ms.
- Implemented role-based access control and laid the groundwork for platform-wide PII redaction, enabling safer data handling across workflows and reporting.
Senior Software Engineer
Rokt - Sydney, Australia
- Developed and maintained a robust frontend SDK, empowering enterprises to deliver targeted advertising seamlessly on e-commerce sites and apps.
- Achieved a 30% reduction in SDK load time and a 40% decrease in script size, significantly improving performance and user experience.
- Built and maintained client-side UI components displayed as offers to customers using React, TypeScript, Redux, and RxJS.
- Adoption at Scale: The SDK is deployed across top-tier companies including Ticketmaster, Best Buy, Domino's, AMC Theatres, and many others, powering customer engagement across millions of users.
- High-Volume Transactions: Design and developed an SDK handling over a million transactions daily, generating of almost $2 million in daily revenue.
- Established and enforced coding standards and best practices to ensure high-quality code and efficient development processes.
- Maintained and monitored app deployments through continuous integration and continuous deployment (CI/CD) pipelines.
- Implemented guardrails by adding integration tests, visual regression tests, and end-to-end tests to ensure application robustness and reliability.
Software Engineer
Leadbook - Singapore
- Managed and mentored a team of Software Engineers, ensuring high-quality deliverables and fostering a collaborative development environment.
- Conducted thorough code reviews among peers to ensure code quality, adherence to best practices, and maintainability, resulting in robust and reliable software deployments.
- Worked closely with product owners and designers, contributing technical expertise and innovative ideas to align with company-wide goals and enhance the overall product vision.
- Co-structured, designed, and built the frontend of the Leadbook platform, delivering a seamless and engaging user experience.
- Spearheaded the reimplementation of the existing platform to a modern single-page application using React, Redux, and Styled Components. This transition improved performance, scalability, and user interaction.
Software Engineer
Tritontek - Cebu, Philippines
- Designed and built a Time Management application specifically tailored for use by Civil Engineers, focusing on usability, efficiency, and reliability.
- Conducted consistent code reviews among peers to ensure high-quality, maintainable, and clean code is deployed. Worked closely with product owners and designers, contributing technical expertise and innovative ideas to align with company-wide goals and enhance the overall product vision.
- Coached and supported teammates through code reviews and whiteboarding sessions, fostering a collaborative and growth-oriented development environment.
- Demonstrated and enforced proper coding techniques, emphasizing maintainability, code reuse, clean code practices, and unit testing. Played a key role in driving and maintaining coding standards within the team.
Recent Blog Posts
•10 min read
Compression, Preloading, and Tree-Shaking: Cutting Load Times by 75% at Lorikeet
How a performance audit uncovered three independent optimizations that cut cold load transfer by 75%, reduced widget load time to 681ms, and trimmed 630KB from our bundles, and how they amplified each other.
Read more•9 min read
Maximizing Productivity with AI Coding Agents
How our team wired Slack, Linear, and Cursor into a delegation pipeline, and why a single agents.md file did more for AI output quality than any tool upgrade.
Read more•8 min read
Claude Skills: Turning Personal Expertise into Team Superpowers
We built around 60 Claude Skills at Lorikeet. Here are the ones that stuck, the structural patterns behind them, and the lessons we learned the hard way.
Read more•8 min read
AI-Assisted Coding Workflows: Delegating vs Leveraging
The mental model I use for AI coding assistants: delegate well-specified tasks and walk away, or leverage AI as a pair for diagnosis and design. Plus the migration that taught me when to switch.
Read more•9 min read
From SDK to SSR: Performance Optimization Lessons Across Frameworks
The instrument-measure-identify-optimize loop I learned building Rokt's SDK, applied to a slow Remix app at Lorikeet: parallel queries, defer, and skeleton UI cut observed page load from 2.2s to ~700ms.
Read moreLet's Connect
I'm always interested in hearing about new opportunities, exciting projects, or just having a friendly chat about technology. Feel free to reach out!
Also available as a Word document.
Location
Sydney, Australia
crisryantan@gmail.com