[eluser]sophistry[/eluser]
welcome loathsome...
you'd be better off putting some details in your post title next time. posts like these tend to get lost in the shuffle.
you should look into "partials", "modules", or "blocks" on the forums and the wiki. there are several ways of structuring getting/building the sidebar only once and then stuffing it in place.
the best way is what ever you are comfortable with; however, i'd suggest finding a caching library and simply caching the sidebar view (you need 3rd party code here because CI does not support view caches, only full page caches).
you could also hack up a kind of cache by using the sessions library (may i suggest using the db version rather than the default that stores data directly in the cookie). store your sidebar in the session data.
just implementing caching does not help with the actual streamlining of the code architecture but it will speed things up. organizing code blocks and streamlining their output can be done with Modular Extensions - a drop-in set up that allows you to nest controller output.
let us know how it goes.
