Issue 14204 fix data grid view excessive cpu+memory usage

[LeafShi1]

Fixes #14204

Root Cause

The foreach loop over DataGridViewRowCollection uses an enumerator that calls this[index], which unshares (clones) each shared row. For 700k rows, this causes massive memory allocation and CPU usage.

Proposed changes

• DataGridView.Methods.cs:
  • Added ReleaseRowUiaProviders() helper method
  • Modified ReleaseUiaProvider() to use HashSet deduplication instead of foreach
• DataGridViewColumnCollection.cs:
  • Modified RemoveAtInternal() to use HashSet deduplication

Customer Impact

• Applications with large DataGridView (700k+ rows) freeze for several seconds when closing forms or removing columns

Regression?

• Yes (The regression was introduced in this commit)

Risk

• Minimal

Screenshots

Before

Closing a form with 700k rows causes 5-10+ seconds of UI freeze and high memory spike due to row cloning.

After

Form closes near-instantly with minimal memory overhead.

Test methodology

• Manual test

Test environment(s)

• .net 11.0.0-alpha.1.26057.107

Microsoft Reviewers: Open in CodeFlow

[LeafShi1]

This fix requires further testing.