Migrating Questrade Edge Mobile to a Faster, More Scalable Architecture

Questrade, one of Canada's leading online brokerages, wanted to improve the performance of its active-trader focused mobile app, Edge Mobile, a trading platform leveraged daily by thousands of Canadian investors to monitor and trade stocks and ETFs on the go, commission-free. The app streams large volumes of market data every second and displays it across multiple interactive views, including watchlists, option chains, and order entry screens.

While their in-house team had already addressed the obvious performance wins, deeper architectural constraints and high-frequency rendering still caused issues: delayed startup times, UI stutter, and missed taps during heavy data streaming.

Questrade needed a partner who could not only solve these problems but also transfer the know-how to their own engineers.

Performance audit and root cause mapping

We began with a full technical audit, profiling load times, CPU and memory usage, and rendering patterns in high-traffic features.

Using tools like React Profiler, Flashlight, and native performance monitors, we traced bottlenecks to:

• JSON bridge serialization overhead from native-to-JS data streaming
• Redundant re-renders triggered by global context changes
• Over-rendering of off-screen table columns
• Repeated network calls that could be cached

Scoped, high-impact fixes

We grouped solutions by complexity and business impact, delivering changes in tight collaboration with Questrade’s dev team:

• TurboModule for gRPC streaming eliminated JSON bridge overhead, reducing CPU usage by 28% in Option Chain.
• React 18 Transitions for non-urgent updates improved interaction responsiveness under load.
• List virtualization for horizontal columns removed unnecessary rendering until the user scrolled, cutting 5–9 seconds of high CPU activity.
• TanStack Query for caching and fetch efficiency reduced backend calls and symbol lookup delays.
• Removed redundant skeleton loaders 90% faster Order Entry load times.
• Enabled Hermes on iOS and optimized state/context logic lower CPU spikes and smoother animations.

Knowledge transfer

We annotated profiling sessions and worked alongside Questrade’s engineers so they could apply the same performance engineering practices in future projects.

Our work delivered measurable improvements in speed, responsiveness, and stability, making Questrade Edge Mobile noticeably smoother to use during high-volume trading sessions.

Key outcomes included:

• Faster startup and navigation across core flows like watchlists, option chains, and order entry
• Smoother interactions under heavy streaming, with fewer missed taps and stutters
• Lower CPU usage across critical screens, improving performance on lower-end devices
• Prepared the app for React Native’s New Architecture and concurrent rendering

These changes not only improved day-to-day usability but also set the foundation for long-term scalability, faster feature delivery, and a better overall user experience, reflected in more positive user reviews and community feedback.