Tax Loopholes

So I've been exploring some other blogs, to diversify the economic literature that I read.  After a discussion on economics with a friend who's on the more conservative side of things, I figured I should read some (respected) conservative/libertarian blogs, and Cafe Hayek seems to be the trick.  I have yet to read anything that I consider beneficial to my knowledge of economics, but I do find several posts worth commenting on.  This one on tax loopholes brings up a good point.  Governments, you would think, are trying to be efficient, so there aren't technically any tax loopholes.  This makes some sense (Donald Boudreaux points out that this is not saying the tax code is optimal).  However, what does this say about Ryan's budget plan?  How do we offset the losses in tax revenue from decreasing top level tax rates by closing "loopholes"?  Are we looking at deductions which could make the poor suffer?  I hope Bourdeaux has a serious talking with Ryan...