-<dd><p>This option will enable compiler
-options and macros to aid in debugging the Mesa libraries.</p>
-</dd>
+<dd><p>This option will set the compiler debug/optimisation levels (if the user
+hasn't already set them via the CFLAGS/CXXFLAGS) and macros to aid in
+debugging the Mesa libraries.</p>
+
+<p>Note that enabling this option can lead to noticeable loss of performance.</p>