[Performance] Export-AzRetirementReport accumulates and copies arrays inefficiently

[cocallaw]

Summary

Export-AzRetirementReport uses $allRecs += $Recommendations (array concatenation) in its process block, which creates a new array on every pipeline input. It then creates additional full copies for transformation and CSV sanitization.

Impact

For large recommendation sets, this causes O(n²) memory allocation from += and multiple full-set copies during export.

Location

• Public/Export-AzRetirementReport.ps1
  • += accumulation: line 39
  • Transformation copy: lines 53–81
  • CSV sanitization copy: lines 86–107

Suggested fix

Use [System.Collections.Generic.List[object]] instead of +=:

begin {
    $allRecs = [System.Collections.Generic.List[object]]::new()
}

process {
    foreach ($rec in $Recommendations) {
        $allRecs.Add($rec)
    }
}

For the transform and sanitize steps, consider processing items inline per format rather than creating separate full copies of the dataset.