Why is Debug Mode slower than Release in VS?

visual-studio-2010

Solution

Debug mode has all optimizations turned off, to make sure the connected debugger works as expected. A Release will have a lot of optimizations switched on.

Simpler than that I cannot state it.

Problem

I've Googled this already and usually the responses are fairly complex and I don't really understand all the jargon. Is there a simple explanation for why Debug mode is so slow? Why not just always run in Release?

Original source