using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        for ( int i = 0; i < 10000000; i++ )

        {

            GetPercentageRoundsImproved(0.4);

        }

    }

​

    private static string GetPercentageRounds(double percentage)

    {

        if (percentage == 0)

            return "⚪⚪⚪⚪⚪⚪⚪⚪⚪⚪";

        if (percentage > 0.0 && percentage <= 0.1)

            return "🔵⚪⚪⚪⚪⚪⚪⚪⚪⚪";

        if (percentage > 0.1 && percentage <= 0.2)

            return "🔵🔵⚪⚪⚪⚪⚪⚪⚪⚪";

        if (percentage > 0.2 && percentage <= 0.3)

            return "🔵🔵🔵⚪⚪⚪⚪⚪⚪⚪";

        if (percentage > 0.3 && percentage <= 0.4)

            return "🔵🔵🔵🔵⚪⚪⚪⚪⚪⚪";

        if (percentage > 0.4 && percentage <= 0.5)

            return "🔵🔵🔵🔵🔵⚪⚪⚪⚪⚪";

        if (percentage > 0.5 && percentage <= 0.6)

            return "🔵🔵🔵🔵🔵🔵⚪⚪⚪⚪";

        if (percentage > 0.6 && percentage <= 0.7)

            return "🔵🔵🔵🔵🔵🔵🔵⚪⚪⚪";

        if (percentage > 0.7 && percentage <= 0.8)

            return "🔵🔵🔵🔵🔵🔵🔵🔵⚪⚪";

        if (percentage > 0.8 && percentage <= 0.9)

            return "🔵🔵🔵🔵🔵🔵🔵🔵🔵⚪";

        return "🔵🔵🔵🔵🔵🔵🔵🔵🔵🔵";

    }

​

    // The blue dot takes up to much memory for a char literal, and is therefore counted as 2 chars.

    private static string GetPercentageRoundsImproved(double percentage) => String.Concat(Enumerable.Repeat("🔵", (int)Math.Round(percentage * 10))).PadRight(10 + ((int)Math.Round(percentage * 10)), '⚪');

}