Modern development tools have normalized lag. As an industry, we’ve somehow accepted that opening a text editor should consume 2GB of RAM, and that typing rapidly should occasionally stutter while an extension parses a JSON tree on the UI thread.

The standard playbook for building cross-platform editors today is to use Web Technologies (Electron/Tauri) or to drag along a decades-old monolithic C++ architecture.

But when it comes to high-performance, memory-intensive data processing, C# and .NET 10 are absolute bare-metal contenders. We don't need to default to browser engines or Rust to get sub-millisecond startup times and zero-allocation execution.

To prove it, I wrote SpanCoder: a cutting-edge, extensibility-first IDE built entirely on .NET 10 and Avalonia UI. It features a custom Skia-rendered canvas, a zero-allocation piece-table text buffer, hardware-accelerated SIMD parsing, and a heavily decoupled process architecture.

Here is how you build a premium, out-of-process IDE with C# without waking up the Garbage Collector.