Optimization of "gui sim update" needed when large groups of units are selected.

[RefinedCode]

If you open up the in game profiler, and then select a large number of units you can see a huge increase to "gui sim update". In my case selecting 100 Longbowmen causes the msec/turn to increase from ~1 to ~48 which is more than a third of what the rendering takes. This causes a very noticeable choppiness in game. It has nothing to do with the status bar or highlight that get rendered but I believe it occurs in the updateSelectionDetails function in binaries/mods/public/gui/session/selection_details.js because disabling some of the function calls (like updating the multiple unit panel) start decreasing the load. I couldn't figure out how to fix this issue though so hopefully someone else can optimize this area?

There is a much larger performance hit when the jsdebugger is enabled but when I took my measurements when it was off, so it would be a pretty good performance increase if the cause of this lag is fixed.