What then is the most efficient and economic (in terms of complexity and speed) way to generate a colored background for it? 

I know I can use \framed, but this I wish to avoid because it seems overly complex for this simple task and may have side effects in terms of alignment issues.

Is the best perhaps using a metapost graphic? and if so, what is best MPgraphic, useMPgraphic, reuseMPgraphic, etc.?