Title says it all, I'm looking for a port of Optifine to Bukkit (built in would be fantastic) or a .jar which you drop in, loads a config, which then allows you to edit things to :True or :False Or :Quick to efault etc
If I understand what your request is, you would need a probably modified version of Spout to interact with the client-side settings for Optifine. You would need access to the config file for Optifine which is client side, and the user would need Optifine.
Most of what optifine does as far as I know is disable graphical features (or change them) to use less resources on the computer. The server doesn't use graphics so I don't see what you mean by that.
Can't Optifine make chunk loading multi-threaded? If it were possible I imagine that would make a great performance enhancer!
If you have optifine in the client you do not need to install it into the server. I am running a server and I can join it fine with optifine installed on my client. If that's what you want to know.
There are several plugins that significantly decrease the amount of resources Bukkit servers use. NoLagg is a good one.