static Dictionary<ReportType, Action> dictReports = new Dictionary<ReportType, Action>();
static void Main(string[] args)
{
    Reporter reporter = new Reporter();
    dictReports.Add(ReportType.Daily, new Action(reporter.GetDailyReport));
    dictReports.Add(ReportType.Weekly, new Action(reporter.GetWeeklyReport));
    dictReports.Add(ReportType.Monthly, new Action(reporter.GetMonthlyReport));
    dictReports.Add(ReportType.Annual, new Action(reporter.GetAnnualReport));

    Stopwatch stopwatch = new Stopwatch();
    stopwatch.Start();

    for (long i = 0; i < 100000000; i++)
    {
        dictReports[ReportType.Weekly]();
    }

    stopwatch.Stop();
    Console.WriteLine($"Time elapsed (dictionary): {stopwatch.Elapsed}");

    stopwatch = new Stopwatch();
    stopwatch.Start();

    for (long i = 0; i < 100000000; i++)
    {
        PrepareReport(ReportType.Weekly);
    }

    stopwatch.Stop();
    Console.WriteLine($"Time elapsed (if): {stopwatch.Elapsed}");
    Console.ReadLine();
}