diff --git a/config.org b/config.org
index e8ef02b..3433b24 100644
--- a/config.org
+++ b/config.org
@@ -638,22 +638,42 @@ As an alternative to ivy/counsel/swiper?
 * Selectrum & Co.
 Uses default features of emacs instead of bringing a new framework in like helm or counsel
 #+begin_src emacs-lisp
+;; either selectrum or vertico
 (use-package selectrum
   :ensure t
   :config
   (selectrum-mode)
-  )
+ )
 
+;; as of 2021-10-29 debian emacs 27.1 seems to cause error
+;; error in post-command-hook (vertico--exhibit): (wrong-type-argument .....)
+;; see https://github.com/minad/vertico/issues/41
+;(use-package vertico
+;  :ensure t
+;  :init
+;  (vertico-mode))
+
+;; orderless orders by recency
+;; prescient orders by frequency
+;; both combined order by frecency (most recent first, then by frequency, then by length)
 (use-package orderless
   :ensure t
+  :config
+  ;; optional performance optimizaion
+  ;; by highlighting only visible candidates
+  (setq orderless-skip-highlighting (lambda () selectrum-is-active)
+        selectrum-highlight-candidates-function #'orderless-highlight-matches
+        completion-category-defaults nil
+        completion-category-overrides '((file (styles . (partial-completion)))))
   :custom
   (completion-styles '(orderless))
+  (savehist-mode)
   )
 
 (use-package selectrum-prescient
   :ensure t
   :config
-  (setq selectrum-prescient-enable-filtering nil)
+  (setq selectrum-prescient-enable-filtering nil)  ; only if used with orderless
   (selectrum-prescient-mode)
   (prescient-persist-mode)
   )