If your debug build is faster than 25% the speed of your release build, you're not doing enough debug checking. Buy your devs faster computers.
Here's an old blog post on the subject. I stick by it:
https://tomforsyth1000.github.io/blog.wiki.html#%5B%5BLogging%2C%20asserts%20and%20unit%20tests%5D%5D