Typing becomes slow with large contenteditable content

Phenomenon

When a contenteditable region contains a large amount of content (thousands of DOM nodes), typing becomes noticeably slow. There is a visible lag between pressing keys and seeing characters appear.

Reproduction example

1. Create a contenteditable div.
2. Insert a large amount of content (e.g., 10,000+ DOM nodes).
3. Place the caret at the end of the content.
4. Start typing rapidly.
5. Observe the delay between keypress and character appearance.

Observed behavior

• In Chrome, typing becomes slow when the contenteditable contains many DOM nodes.
• There is a noticeable lag between keypress and character rendering.
• The browser may become unresponsive during rapid typing.

Expected behavior

• Typing should remain responsive regardless of content size.
• The browser should optimize rendering for large contenteditable regions.
• Performance should degrade gracefully, not abruptly.