[Gul Banana]

Make sure to read all of these instructions before following them!
Step 1: Log in as an admin user.
Explanation: You will need to edit the actual kernel of the OS, which requires admin privileges.
Step 2: Open Terminal
Explanation: The "strip" program, which you are going to use, is commandline-only.
Step 3: Enter the command "sudo strip /mach_kernel" and then, when prompted, your password.
Explanation: From the "strip" man page:

strip removes or modifies the symbol table attached to the output of the assembler and link editor. This is useful to save space after a program has been debugged and to limit dynamically bound symbols.

Step 4: Now that you have carefully read all the instructions before following any of them, do not follow any (except this one).
Explanation: strip really will remove the "debug symbols" from your kernel, reducing its size and making it run faster - but extensions and the IOKit require those symbols to link to the kernel at runtime, and stripping mach_kernel will render your system unbootable.
Unbootable... but sans debug code! Finally!

[Wevah]

Ahahahaha!

[Eriamjh]

...Unbootable... but sans debug code! Finally!

I can do that just by deleting the kernel all together.

[Jan Van Boghout]

Good thing you didn't post these instructions in the Software forum, it might have turned out to be a worthy sudo rm debacle successor

[arekkusu]

On a more serious note,

there is a difference between debug code, debug symbols, debug resources, and unoptimized code.

Apple isn't totally stupid, usually. They remove the first two. They seem to miss the third one quite often. They are slowly improving on the fourth.