Just see render logs from browser:
Vaadin 7
INFO: Making UIDL Request with params: 30ae1a56-3f76-4441-b30d-cb5f2217bc1b[["269","com.vaadin.shared.ui.button.ButtonServerRpc","click",[{"clientX":"260", "metaKey":false, "clientY":"174", "relativeX":"41", "relativeY":"18", "shiftKey":false, "altKey":false, "ctrlKey":false, "type":"1", "button":"LEFT"}]
]]
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: Server visit took 1297ms
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: JSON parsing took 0ms
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: Handling message from server
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Handling resources from server
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Handling type inheritance map from server
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: Handling type mappings from server
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: Handling resource dependencies
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Handling type mappings from server completed: 15 ms
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Handling meta information
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Creating connectors (if needed)
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Updating connector states
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Handling locales
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Updating connector hierarchy
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Sending hierarchy change events
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Running @DelegateToWidget
Thu Oct 10 14:13:52 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Sending state change events
Thu Oct 10 14:13:53 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Passing UIDL to Vaadin 6 style connectors
Thu Oct 10 14:13:59 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Performing server to client RPC calls
Thu Oct 10 14:13:59 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Unregistered 0 connectors
Thu Oct 10 14:13:59 GMT+300 2013 com.vaadin.client.VConsole
INFO: handleUIDLMessage: 6750 ms
Thu Oct 10 14:13:59 GMT+300 2013 com.vaadin.client.VConsole
INFO: Starting layout phase
Thu Oct 10 14:13:59 GMT+300 2013 com.vaadin.client.VConsole
INFO: Measured 58 non connector elements
Thu Oct 10 14:14:04 GMT+300 2013 com.vaadin.client.VConsole
INFO: Pass 1 measured 153 elements, fired 48 listeners and did 12 layouts.
Thu Oct 10 14:14:04 GMT+300 2013 com.vaadin.client.VConsole
INFO: Pass 2 measured 36 elements, fired 7 listeners and did 3 layouts.
Thu Oct 10 14:14:05 GMT+300 2013 com.vaadin.client.VConsole
INFO: Pass 3 measured 11 elements, fired 5 listeners and did 3 layouts.
Thu Oct 10 14:14:06 GMT+300 2013 com.vaadin.client.VConsole
INFO: Pass 4 measured 7 elements, fired 3 listeners and did 2 layouts.
Thu Oct 10 14:14:06 GMT+300 2013 com.vaadin.client.VConsole
INFO: Pass 5 measured 6 elements, fired 1 listeners and did 1 layouts.
Thu Oct 10 14:14:07 GMT+300 2013 com.vaadin.client.VConsole
INFO: No more changes in pass 6
Thu Oct 10 14:14:07 GMT+300 2013 com.vaadin.client.VConsole
INFO: Total layout phase time: 7969ms
Thu Oct 10 14:14:07 GMT+300 2013 com.vaadin.client.VConsole
INFO: * Dumping state changes to the console
Thu Oct 10 14:14:07 GMT+300 2013 com.vaadin.client.VConsole
INFO: Processing time was 15359ms for 17848 characters of JSON
Vaadin 6
INFO: Variable burst to be sent to server:
INFO: PID537 (class com.vaadin.terminal.gwt.client.ui.VButton) :
INFO: state (b) : true
INFO: mousedetails (s) : 0,328,174,false,false,false,false,1,68,16
INFO: Making UIDL Request with params: 7cc33692-2552-48ab-b7bb-812f4be9b74ctruePID537stateb0,328,174,false,false,false,false,1,68,16PID537mousedetailss
INFO: Server visit took 626ms
INFO: JSON parsing took 1ms
INFO: 228px:228:228
INFO: updateFromUIDL: 27,[object Object]
INFO: updateFromUIDL: 15,[object Object]
INFO: Processing time was 1313ms for 15028 characters of JSON
INFO: Referenced paintables: 115
It is the epic fail.
Time to open screen changed from 1313ms to 7969ms.
How to optimize it?
I have tried to build optimized widget set - no effect. I have tried to build monolithic widgetset - no effect.