A Very Strange Chart Delay Problem. Is this a Microsoft issue?

[kubota1000]

I'm hoping you may be able to confirm if a very strange Excel 2007 and Excel 2010 charting delay problem is a problem which Microsoft needs to resolve. I'm using Windows 7 32-bit.

I'm presently running Excel 2010. The attached workbook has a chart function to display a selected function f(x) between two given limits. The charting parameters are under Name Manager, and conditional formatting is used to select the desired function and parameters.

To demonstrate the problem:

1. Open the workbook and enable macros.
2. Click the Show Chart button. The chart window is opened, and the selected function plot is immediately displayed over the given limits.
3. Click an up or down arrow button ONCE to select the adjacent function. The chart takes about 2 seconds for the new function plot to appear.
4. Again, click an up or down arrow button ONCE to select the adjacent function, and the new plot appears immediately. NO delay.
5. All further arrow clicks change the chart immediately - NO delay.
6. Click the Hide Chart button to hide the chart. The delay is now again ready to appear, as repeating steps 2 and 3 will confirm.

7. Click the Show Chart button to enable the chart. The selected function plot is displayed.
8. Click an arrow button TWICE quickly. The chart is updated immediately to the selected function. NO delay.
9. All further arrow clicks show no delay.

I have not been successful in finding and fixing the cause for the 2 second delay. Also, the attached workbook is a most basic workbook.

This delay problem previously and randomly occurred under Excel 2007, where it may run for a few weeks without the delay, and then the delay returns without warning. Just as unexpectedly, some days or weeks later, the delay may disappear, with no action at any time on my part which would be considered associated with the charting function.

After upgrading to Excel 2010 a few days ago, the delay problem showed up immediately it was run for the first time, and has remained, even though it had not previously been showing up under Excel 2007 for several weeks.

I have searched for this very strange symptom on the Internet without success, and I'd be most grateful for any advice on how to remove this unwanted delay.

Thanks