diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index 4f222b4cf5..3239722981 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -3841,6 +3841,8 @@ python-shell-completion-get-completions
         (split-string completions
                       "^'\\|^\"\\|;\\|'$\\|\"$" t)))))
 
+(defvar-local python-shell--capf-cache nil)
+
 (defun python-shell-completion-at-point (&optional process)
   "Function for `completion-at-point-functions' in `inferior-python-mode'.
 Optional argument PROCESS forces completions to be retrieved
@@ -3895,11 +3897,13 @@ python-shell-completion-at-point
                        #'ignore
                      #'python-shell-completion-get-completions))
                   (t #'python-shell-completion-native-get-completions)))))
-    (list start end
-          (completion-table-dynamic
-           (apply-partially
-            completion-fn
-            process import-statement)))))
+    (let  ((re (or (car python-shell--capf-cache) regexp-unmatchable))
+           (prefix (buffer-substring-no-properties start end)))
+      (unless (string-match re prefix)
+        (setq python-shell--capf-cache
+              (cons (concat "\\`" (regexp-quote prefix) "\\(?:\\sw\\|\\s_\\)*\\'")
+                    (funcall completion-fn process import-statement prefix)))))
+    (list start end (cdr python-shell--capf-cache))))
 
 (define-obsolete-function-alias
   'python-shell-completion-complete-at-point