Improve performance of the API returned by `createTextWriter`

[dmichon-msft]

Suggestion

🔍 Search Terms

List of keywords you searched for before creating this issue. Write them down here so that others can find this suggestion more easily and help provide feedback.

• performance
• createTextWriter

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

Based on the performance wins in #44031 / #43987, there may be opportunities to improve the performance of concatenating lots of short strings in the createTextWriter() API.

📃 Motivating Example

Compiler performance. Currently print takes substantially longer than parse, so anything to improve print time without sacrificing code maintainability is a worthwhile endeavor.

💻 Use Cases

Compiler performance

[dmichon-msft]

Seems to be about as good as we are going to get for the moment. The optimization linked only really holds when concatenating a large number of single-byte strings. Short of having the compiler directly operate in UTF-8 space instead of string-space, seems unlikely that we can improve things here much if at all.