diff --git a/README.org b/README.org
index 9ff6992..e7a69c8 100644
--- a/README.org
+++ b/README.org
@@ -20,7 +20,7 @@ It is also available on [[https://melpa.org/#/eldoc-box][MELPA]].
 
 ** Function
 - =eldoc-box-hover-mode= :: Display documentation of the symbol at point in a childframe on upper corner.
-- =eldoc-box-hover-at-point-mode= :: Same as =eldoc-box-hover-mode= except the childframe is displayed at point, instead of on the upper corner.
+- =eldoc-box-hover-at-point-mode= :: Same as =eldoc-box-hover-mode= except the childframe is displayed at point, instead of on the upper corner. /Note that this mode brings a small but noticeable slowness./
 - =eldoc-box-eglot-help-at-point= :: See below.
 ** Face
 -  =eldoc-box-border= :: Adjust =:background= of this face for border color.