Thanks Mahdi,
Yes. The WMSOverlay has better performance than the WMSLayer. Because we did some optimization for the WMSOverlay such as using multiple threading. WMSOverlay is not able to be added to the PrinterInteractiveOverlay. But we are doing some enhancement for the WMSlayer right now. Hopefully this will get PrinterInteractiveOverlay perform better if we have the WMSLayer in it. We will let you know once the wmslayer enhancement done.