PDF annotation tools are notoriously slow. LeedPDF is different - it's fast, even with large documents. Here's how we did it.
Rendering Optimization
We use canvas-based rendering with intelligent caching. Pages are rendered on-demand and cached, so scrolling through a document feels instant. We also use web workers to handle PDF parsing without blocking the UI.
Memory Management
Large PDFs can consume a lot of memory. We implement smart memory management: pages are unloaded when not visible, and we use efficient data structures to store annotations.