command that has a non-@code{nil} @code{scroll-command} property.
@xref{Property Lists,,, elisp, The Emacs Lisp Reference Manual}.
+@vindex fast-but-imprecise-scrolling
+ Sometimes, particularly when you hold down keys such as @kbd{C-v}
+and @kbd{M-v}, activating keyboard auto-repeat, Emacs fails to keep up
+with the rapid rate of scrolling requested; the display doesn't update
+and Emacs can become unresponsive to input for quite a long time. You
+can counter this sluggishness by setting the variable
+@code{fast-but-imprecise-scrolling} to a non-@code{nil} value. This
+instructs the scrolling commands not to fontify (@pxref{Font Lock})
+any unfontified text they scroll over, instead to assume it has the
+default face. This can cause Emacs to scroll to somewhat wrong buffer
+positions when the faces in use are not all the same size, even with
+single (i.e., without auto-repeat) scrolling operations.
+
@vindex scroll-up
@vindex scroll-down
@findex scroll-up-line