Ah, no, what you do is:

In the same directory where you ran cmake originally, run "ccmake ." - that will open a GUI-like interface to configure the build. You have to press "t" to toggle the advanced options, then you should be able to find the two variables I mentioned.

After adding the optimization settings, also change "BUILD_TYPE" to "Release" for activating compiler optimizations.

Then press "c" for "configure", after which you can exit the GUI via "q" and re-run "make"

Hope this all makes sense. :-) 

Torsten