Autotool uses -g -O2 + a huge set of warning flags by default.
Using scripts/bootstrap.sh, we have a choice to optimize or not (-O2 vs. nothing). This script uses -ggdb instead of -g (not a big diffenerce) and the same warning options.
SOURCE_BROWSER Doxygen switch is configurable from CMAKE. This option includes a syntax highlighted and cross linked copy of the source files into the doc. A useful option but it makes the doc much larger and it will takes more time to build the doc.