[TACHYON-220] WIP Comments describing issues and possible solutions 

Some initial comments to help improve the performance of master info. From what I gather there is locking on stack local objects that are never really put back into the map. I would appreciate suggestions before implementing it, hence the WIP tag.
Not true. At least in this diff I have yet to see a explict copy so all mutations will be seen from asking for the object again from the map