damn it :-(
i guess you should raise OSS then so that someone can take a closer look.
Meanwhile, you can continue using personas with that transaction parameter i told you.
Based on your snapshot, you are getting like ~90 MB of data for your SMEN transaction (which might be creating some bottleneck). And thats because may be, you have lot of child nodes in the SMEN tree structure you see on the left. Again, thats my asusmption.
Have you also made sure that compression in ON for your restgui service?
Once more, please try again by switching to both User menu <--> SAP Menu. I am hoping that one of your menu will have less children in tree control you see on the left.
lastly,probably also try using any other user.
Regards,
Sushant