diff --git a/settings/org-settings.el b/settings/org-settings.el
index 988ff4da..cf8a7ec6 100644
--- a/settings/org-settings.el
+++ b/settings/org-settings.el
@@ -743,8 +743,8 @@ Suggest the URL title as a description for resource."
   :after (org))
 
 (use-package ob-core
-  :defer t
-  :hook (org-babel-after-execute . org-redisplay-inline-images)
+  ;; :hook (org-babel-after-execute . org-redisplay-inline-images)
+  :commands (by-backend svg-fname)
   :config
   (setq org-babel-inline-result-wrap "%s")     ;; default "=%s="
   (setq org-confirm-babel-evaluate nil)        ;; no "Evaluate this gnuplot code block on your system? (y or n)"
@@ -755,20 +755,7 @@ Suggest the URL title as a description for resource."
 The key of plist elements is one of the following lisp symbols:
 html, latex, ascii, or t (meaning all other cases).  If BODY is
 nil the return value is nil"
-    `(case org-export-current-backend ,@body))
-
-  ;; obsolete function
-  (defalias 'if-latex 'by-backend)
-  (make-obsolete 'if-latex 'by-backend "2020.09.07")
-  (advice-add 'if-latex :before
-              (lambda (&rest r)
-                "Warning: Function `if-latex' is obsolete.
-Probably used inside an org file for a src block and/or for an org export.
-Updating an old preamble.org should remove this warning."
-                (message "Warning: Function `if-latex' is obsolete.
-Probably used inside an org file for a src block and/or for an org export.
-Updating an old preamble.org should remove this warning."))
-              '((name . "obsolete")))
+    `(cl-case org-export-current-backend ,@body))
 
   ;; TODO: still useful?
   (defun svg-fname (filename)
@@ -807,7 +794,7 @@ Updating an old preamble.org should remove this warning."))
     (add-to-list 'org-babel-load-languages '(ditaa . t))))
 
 (use-package ob-gnuplot
-  :defer t
+  :commands (gpl-file gpl-term)
   :init
   (with-eval-after-load 'org
     (add-to-list 'org-babel-load-languages '(gnuplot . t)))
@@ -831,7 +818,10 @@ set linetype 5 lc rgb '#76ab2f' lw 2 pt 5 ; \
 set linetype 6 lc rgb '#4cbded' lw 2 pt 5 ; \
 set linetype 7 lc rgb '#a1132e' lw 2 pt 5 ; \
 filter(x,min,max) = (x >= min && x <= max) ? x : 1/0 ; \
-set datafile separator '\\t'  # treat empty fields in a org-table as 'missing' rather than 'bad' (ignoring, shifting column) ")
+set datafile separator '\\t'  # treat empty fields in a org-table as 'missing' rather than 'bad' (ignoring, shifting column) "
+    "usage e.g. to prepend style for all gnuplot src blocks by-backend:
+#+property: header-args:gnuplot :prologue (by-backend (latex gnuplot-init-light) (t gnuplot-init-dark))
+")
   (defvar gnuplot-init-dark "reset ; \
 theme_type = 'dark' ; \
 set border lc rgb '#cccccc' ; \
@@ -850,7 +840,10 @@ set linetype 5 lc rgb '#cc5279' lw 2 pt 5 ; \
 set linetype 6 lc rgb '#76ab2f' lw 2 pt 5 ; \
 set linetype 7 lc rgb '#ecb01f' lw 2 pt 5 ; \
 filter(x,min,max) = (x >= min && x <= max) ? x : 1/0 ; \
-set datafile separator '\\t'  # treat empty fields in a org-table as 'missing' rather than 'bad' (ignoring, shifting column) ")
+set datafile separator '\\t'  # treat empty fields in a org-table as 'missing' rather than 'bad' (ignoring, shifting column) "
+    "usage e.g. to prepend style for all gnuplot src blocks by-backend:
+#+property: header-args:gnuplot :prologue (by-backend (latex gnuplot-init-light) (t gnuplot-init-dark))
+")
   
   (defun gpl-file (filename)
     "\
@@ -887,7 +880,7 @@ usage: #+HEADER: :term (gpl-term \"15cm,12cm\" \"380,300\")
   )
 
 (use-package ob-latex
-  :defer t
+  :commands (tpl-file gpl-results)
   :config
   ;; tikz config for own org export projects
   (defun tpl-file (filename)
@@ -1058,7 +1051,8 @@ usage: #+HEADER: :results (tpl-results)
   )
 
 (use-package ob-python
-  :after (org-src python)
+  ;; :after (org-src python)
+  :commands (mpl-var mpl-prologue)
   ;; :commands (org-babel-execute:python
   ;;            org-babel-variable-assignments:python)
   :init