It is difficult to tell the issue just looking at your code, especially that we don't know what's on the different ToolWindows (e.g. PieObject, LineObject). Is it ToolWindows with charts having a heavy loads of data points for example?
What we can say is that we don't experience this behavior here. It would be best if you could send us a sample application reproducing the issue, at email@example.com, so we can investigate this further. Please provide a link to the present post in your email.
Xceed Software Inc.