Release vs Debug Build Times

I have always believed that Debug builds are slower than Release builds since the compiler needs to additionally generate debugger information. I was recently surprised to hear one of my colleagues saying that release builds usually take more time. (I believe that it is only because of incremental linking/compiling).

In general, which of the two is faster?

Well, there are a number of variables that could affect things. Here are some reasons Debug could be faster:

• Usually Debug mode does a lot less optimizations, as those can mess up the mapping between instructions and lines of code. So, the compiler is doing less work there.
• Even if a full debug build is slower, Debug builds happen a lot more often and can usually take advantage of incremental builds a lot more than Release build can. So fairly often a Debug build doesn't have to do nearly as much work as a Release build would.