Laggy `DiffRenderer` UI when diff text is large

[xinnjie]

When the diff text is large, the DiffRenderer UI becomes laggy.

Proposed Solution: Run DiffParser.parse in the background, and add an intermediate state in DiffRenderer to display ProgressView.

If the solution seems good to you , I can make a PR @tornikegomareli

[tornikegomareli]

When the diff text is large, the DiffRenderer UI becomes laggy.

Proposed Solution: Run DiffParser.parse in the background, and add an intermediate state in DiffRenderer to display ProgressView.

If the solution seems good to you , I can make a PR @tornikegomareli

Sounds good, looking forward to your PR

[tornikegomareli]

Merged it.