Financial applications cannot rely on standard HTTP request/response cycles. If a user has to refresh the page to see a price change, the platform is already obsolete.
I designed a highly concurrent architecture using Node.js for the main server, Redis for fast in-memory pub/sub message brokering, and WebSockets (Socket.io) to push binary market data directly to the React client.
When a user places a trade, speed and reliability are paramount. The order is instantly validated on the backend and pushed to the matching engine.
Rendering thousands of data points on a frontend chart (like TradingView or custom Canvas charts) causes massive DOM bottlenecking if done incorrectly.
To solve this, I completely bypassed React's standard rendering cycle for the charts. Instead, incoming socket data is fed directly into a raw HTML5 `<canvas>` context. This ensures steady 60FPS animations even when the market is highly volatile and receiving hundreds of ticks per second.