How to make MSVC debug builds run faster

Question

We have a large C++ application, which sometimes we need to run as a debug build in order to investigate bugs. The debug build is much much slower than the release build, t

Answer 1

there are several difference between debug builds and release builds that influence both debugability and speed. The most important are the _DEBUG/NDEBUG define, the compiler optimizations and the creation of debug information.

You might want to create a third Solution Configuration and play around with these settings. For example, adding debug information to a release build doesn't really decrease performance but you already get a sensible stack trace so you know which function you are in. Only the line information is not reliable because of the compiler optimizations.

If you want reliable line information, go on and turn off optimizations. This will slow down the execution a bit but this will still be faster than normal debug as long as the _DEBUG define is not set yet. Then you can do pretty good debugging, only everything that has "#ifdef _DEBUG" or similar around it won't be there (e.g. calls to assert etc.).

Hope this helps,

Jan