Thin client on comfort panel working very slowly

I made a test connecting a comfort panel 1200 to an ITC 1200.  In the test the PLC was not connected. 

The thin client on comfort panel was also working very slowly (6 seconds to navigate to a new screen).  Also the comfort panel with the smart server is working slower with thin clients then without. It took about 1s to navigate to another screen.  Someone suggests that the comfort panel 1200 is too slow for having thin clients and that our WinnCC application is too heavy.  We have indeed many power tags (1400) with lots of integers and reals.  And all buttons have an icon and an animation.

Does anybody have a suggestion why it is so slowly? 

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Split from WinCC Runtime in client computers is too slow.