Performance issue with big event count

It seems that there is a significant performance loss, when handling many events, say 1000 and up.
Vertical calendar scrolling gets extremly slow and inresponsive, especially on my older PCs and in Debug version.

Test case:
In CalendarDemo I added the following code in CCalendarDemoDoc::AddTestEvents().
It adds 15 events per day, starting at 6:00am, repeated for last 3000 days.

  // add test events
  COleDateTime dtNow(COleDateTime::GetCurrentTime() + spTimeShift);
  COleDateTimeSpan spDay(1, 0, 0, 0);
  COleDateTimeSpan sp15min(0, 0, 15, 0);
  COleDateTimeSpan spHour(0, 1, 0, 0);

  // NEW -------------- add a few thousand events
  COleDateTime dtInit;
  dtInit.SetDateTime(COleDateTime::GetCurrentTime().GetYear(), COleDateTime::GetCurrentTime().GetMonth(), COleDateTime::GetCurrentTime().GetDay(), 6, 0, 0);
  for (int d = 0; d < 3000; d++) {
    COleDateTimeSpan spD(-d, 0, 0, 0);
    for (int h = 0; h < 15; h++) {
      COleDateTimeSpan spH(0, h, 0, 0);

      CXTPCalendarEventPtr ptrEvent = NewEvent(pCalendarData, dtInit + spD + spH, dtInit + spD + spH + spHour, _T("Test event"), _T("New Location"), nScheduleID);
      ptrEvent->SetBusyStatus(xtpCalendarBusyStatusTentative);   
      if (!pCalendarData->AddEvent(ptrEvent)) {
        ASSERT(FALSE);
        return;
      }
    }
  }
  // END -------------------------------


Set the time scale from 2:00 to 23:00 and switch to Work Week view.


Mark, can you please check if you get this performance loss, too and what's its cause?

Thanx, Marco