*Check the RAM size availability in the Server because of this it takes time to load the object . Once the application gets cache in the server it open up normally and that's what its happening in your case ...
*Same things goes when you restart the server it clears the temp memory and allocates max RAM availability for your app
*If your using calculated dimension or heavy expression in the chart try to handle it in the script
I am still working with support on this issue. The change in the case of the path seems to have been a dead end. I see a change in case even when the issue doesn't occur.
A new issue has started with the same object. Export to excel sometimes fails with an "invalid format" error.
Since these two issues only occur with one document and they have a custom section access implemented, I am beginning to believe the security has something to do with. We are currently removing all security and trying to reproduce the issue.