+75% or more of each image will always be visible. If set to 100%,
+then the images will always fill the screen, and no panning or
+zooming will occur. Images will still smoothly fade from one
+to another, however, assuming \fI\-fade\fP is non-zero.
+.TP 8
+.B \-delay \fInumber\fP
+Per-frame delay, in microseconds. Default: 20000 (0.02 seconds.).
+.TP 8
+.B \-cutoff \fInumber\fP
+If the frame rate drops below this number of frames per second, then
+certain features will be turned off automatically (first zooming,
+then, if the low frame rates persist, fading.) Default 5.
+
+The idea here is that if your machine can't maintain a decent frame
+rate, then it must not have fast 3D hardware, so we might as well
+behave in a simpler manner. Set this to 0 to disable this check.