Not being able to have code that compiles in debug but doesn't in release is a pretty serious issue for CPU-bound performance-critical code. Otherwise, you're g

Not being able to have code that compiles in debug but doesn't in release is a pretty serious issue for CPU-bound performance-critical code. Otherwise, you're going to be commenting things out a lot or using preprocessors, both of which are annoying and slow down development velocity. As an example, checking errors on GPU is enormously slow because you stall the CPU until the hardware FIFO drains every time you do. You can't ship software that checks for errors after issuing each DirectX or OpenGL call. But writing graphics code is also really annoying without a debug mode that checks for errors after each render command, because the failure mode of graphics programs tends to be "black screen" or "screen full of garbage".