Document `org-agenda-ignore-drawer-properties'

* agenda-optimization.org: Document `org-agenda-ignore-drawer-properties'.

agenda-optimization.org

@@ -123,3 +123,14 @@ You can also set this on a per-command basis:
             (org-agenda-use-tag-inheritance nil)))))
 #+END_SRC
 
+* Disable parsing for some drawer properties
+
+Text properties are used to prepare buffers for effort estimates,
+appointments, and subtree-local categories in the agenda.  If you
+don't use some of these agenda features, you can turn them off.
+Since using such drawer properties require a special scan before each
+new agenda command, this can lead to a speedup. For example
+
+#+BEGIN_SRC emacs-lisp
+  (setq org-agenda-ignore-drawer-properties '(effort appt category))
+#+END_SRC