Oh yeah, a great way to ruin someone’s day is a few strings of barbed wire. I suggest barbed wire over c wire for a few reasons, the first is cost, barbed wire is much cheaper, and another big factor is availability. Any hardware store worth it’s salt will carry barbed wire. Barbed can be purchased and stored very easily and hidden very well. It lasts too, as long as it’s stored in a dry place rust won’t become an issue.
Of a barbed wire fence is good at slowing people down, but it can be diverted or cut. A better tactic is to use the fences to funnel people. People in general will pursue the path of least resistance. So if they see a gate, why cut or try to go through the wire. A gate or controlled entry point is makes it very easy to funnel a group or an individual in one area, making it much easier to locate and target a potential threat.
Another way to slow people down is too lay barbed wire down on the ground in very tight lines.
The wire should be lain in strands roughly ten inches apart and a few inches off the ground. This makes it a nightmare to navigate and slows people trying to cross it. This is a similar trick people use to keep deer from their gardens. The wire acts as a potential tripping obstacle, but is easy to spot. So people either have to lift their legs exceptionally high, or trip and fall in the mess. This doesn’t work as a complete barrier, but it does slow potential attackers down. (Again this should be used post collapse, as it opens you up to liability issues and lawsuits.)