Don't calculate strings.ToLower() twice and skip over s == "" to avoid the map lookups and some assignments when already tombstoned and you'll save a lot of tim

Don't calculate strings.ToLower() twice and skip over s == "" to avoid the map lookups and some assignments when already tombstoned and you'll save a lot of time. seen := make(map[string]bool) for n, s := range array { if s == "" { continue } lower := strings.ToLower(s) if seen[lower] { array[n] = "" } else { seen[lower] = true } }