Table Of Contents The Bottleneck Step 1: The Memory Slab Step 2: JSExport Bridge Step 3: DOM Mutation The Performance Payoff Compile-time Generation with Roslyn Try it yourself! The Bottleneck: When WebAssembly UI gets sluggish If you've ever built a heavy data grid, a real-time telemetry dashboard, or a line-of-business spreadsheet application in Blazor WebAssembly, you've likely hit the rendering wall. Blazor WASM is incredibly productive, but when thousands of cells change multiple times a second: Every property change triggers an event. Every event triggers standard Blazor component cycle overhead ( StateHasChanged ). The Virtual DOM (VDOM) diffs the old rendering tree with the new one. JS-Interop serializes the diffs and updates the browser DOM. Under high frequency (like 100+ updates per second on 5,000+ fields), this pipeline stutters. The CPU spikes to 100%, garbage collection (GC) triggers pauses, and key-press latency rises.…