There are no politically viable ways to make the US government significantly more efficient in a way that would leave government services unaffected.

The one big opportunity to do that is defence and it is the one that Republicans, particularly, treat as a sacred cow.

Social Security is already extremely efficient in that the cost of moving money around is minimal.

Medicare and Medicaid are also more efficient than the private sector.

Is government perfect? Hell no. But in the really big picture the big and rising areas of civilian expenditure are not where the inefficiencies lie.

There absolutely are, but not all of them are good ideas for other reasons. One of the big things that I think many "run government like a business"-types fail to consider, is that fairness, equitability, checks-and-balances, democratic process, quality of life, etc are often inherently inefficient.

That is a straw man, and an ugly one at that.

Every system has inefficiencies, including the government.

The fallacy is to assume that businesses inherently have less inefficiencies than government and/or that a government’s cost/benefit equation improves if it’s run as a business. Often, their functions overlap and this can be the case. Automated traffic monitoring is cheaper than having people count cars. But beware privatization that promises efficiency and lower costs—the result is almost always worse services, maintainable debt and in time a government bailout.

Often, their functions do not overlap. The purpose of social security is not to tighten spending as much as possible, it is to improve quality of life as much as possible.