perf: read modified file in buffer format

[Plumbiu]

Description

content is not used if the modified file is empty, we can transform to string after.

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines, especially the Pull Request Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Update the corresponding documentation if needed.
• Ideally, include relevant tests that fail without this PR but pass with it.

[sapphi-red]

• If the content is an empty buffer, then I guess the conversion to '' won't take time.
• If the content has a non-empty buffer, then I guess fs.readFile(, 'utf8') is faster as Node 20.5.0+ has a fast path (fs: add a fast-path for readFileSync utf-8 nodejs/node#48658).

So I think the current implementation is faster.

see sapphi's comment

[Plumbiu]

• If the content is an empty buffer, then I guess the conversion to '' won't take time.
• If the content has a non-empty buffer, then I guess fs.readFile(, 'utf8') is faster as Node 20.5.0+ has a fast path (fs: add a fast-path for readFileSync utf-8 nodejs/node#48658).

So I think the current implementation is faster.

I see, i will close this pr