Do you do this as a part of the development work?
I suspect there is unnecessary traffic between the client and the server - this would explain i.e. some of the dashboard sluggishness.
It's really easy to simulate any level of network connectivity. Use the SpeedLimit OS X Preference add-on and you can set delay + bandwidth range for the system. Try out how bad can you go and still work with the system. Then let us know.

If you already are perfectly optimized, and know exactly what packets run between the client and the server (and they really are all needed) then ... what's wrong with my Dashboard? Any hints on how I can make it snap.
(see, lots of requests for snap these days..)
My connection:
WIFi (full bars) to 10Mbps cable in Helsinki, Finland
p.s. suggestion to Idea Labels: Performance