The reason it's faster is largely because it doesn't have all those little quality of life features and extension ecosystem. It's easyish to make software perform well if it doesn't do all that much. If you take base vscode, no extensions, and just do raw text editing, it's hard for me to tell the difference between vscode, zed, or any other editor.

When vscode was released, Sublime was faster - and it stayed faster. But that wasn't enough to stop the rise of vscode.