Array CountIf Substitute - Count(Match())

Question

Core Question

How can I perform repeated CountIf()s on a range as efficiently (performance-wise) as possible?

Concerns in Detail

Answer 1

Dim rowin as integer 'this is a counter for the row index
For rowin = 2 To Sheets("Sheet1").UsedRange.Rows.Count
Sheets("Sheet1").Range("D" & rowin).Value = WorksheetFunction.CountIf(Range("A:A"), Range("C" & rowin))
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