Index: sys/dev/vt/vt_core.c
===================================================================
--- sys/dev/vt/vt_core.c
+++ sys/dev/vt/vt_core.c
@@ -248,7 +248,8 @@
 vt_resume_flush_timer(struct vt_device *vd, int ms)
 {
 
-	if (!atomic_cmpset_int(&vd->vd_timer_armed, 0, 1))
+	if (!(vd->vd_flags & VDF_ASYNC) ||
+	    !atomic_cmpset_int(&vd->vd_timer_armed, 0, 1))
 		return;
 
 	vt_schedule_flush(vd, ms);
@@ -258,7 +259,8 @@
 vt_suspend_flush_timer(struct vt_device *vd)
 {
 
-	if (!atomic_cmpset_int(&vd->vd_timer_armed, 1, 0))
+	if (!(vd->vd_flags & VDF_ASYNC) ||
+	    !atomic_cmpset_int(&vd->vd_timer_armed, 1, 0))
 		return;
 
 	callout_drain(&vd->vd_timer);
@@ -435,9 +437,11 @@
 
 	if (diff < -size.tp_row || diff > size.tp_row) {
 		vw->vw_device->vd_flags |= VDF_INVALID;
+		vt_resume_flush_timer(vw->vw_device, 0);
 		return;
 	}
 	vw->vw_device->vd_flags |= VDF_INVALID; /*XXX*/
+	vt_resume_flush_timer(vw->vw_device, 0);
 }
 
 static int
@@ -750,6 +754,7 @@
 	struct vt_window *vw = tm->tm_softc;
 
 	vtbuf_cursor_position(&vw->vw_buf, p);
+	vt_resume_flush_timer(vw->vw_device, 0);
 }
 
 static void
@@ -758,6 +763,7 @@
 	struct vt_window *vw = tm->tm_softc;
 
 	vtbuf_putchar(&vw->vw_buf, p, c);
+	vt_resume_flush_timer(vw->vw_device, 0);
 }
 
 static void
@@ -766,6 +772,7 @@
 	struct vt_window *vw = tm->tm_softc;
 
 	vtbuf_fill_locked(&vw->vw_buf, r, c);
+	vt_resume_flush_timer(vw->vw_device, 0);
 }
 
 static void
@@ -775,6 +782,7 @@
 	struct vt_window *vw = tm->tm_softc;
 
 	vtbuf_copy(&vw->vw_buf, r, p);
+	vt_resume_flush_timer(vw->vw_device, 0);
 }
 
 static void
@@ -785,6 +793,7 @@
 	switch (cmd) {
 	case TP_SHOWCURSOR:
 		vtbuf_cursor_visibility(&vw->vw_buf, arg);
+		vt_resume_flush_timer(vw->vw_device, 0);
 		break;
 	case TP_MOUSE:
 		vw->vw_mouse_level = arg;
@@ -887,7 +896,7 @@
 }
 #endif
 
-static void
+static int
 vt_flush(struct vt_device *vd)
 {
 	struct vt_window *vw;
@@ -901,14 +910,14 @@
 
 	vw = vd->vd_curwindow;
 	if (vw == NULL)
-		return;
+		return (0);
 
 	if (vd->vd_flags & VDF_SPLASH || vw->vw_flags & VWF_BUSY)
-		return;
+		return (0);
 
 	vf = vw->vw_font;
 	if (((vd->vd_flags & VDF_TEXTMODE) == 0) && (vf == NULL))
-		return;
+		return (0);
 
 #ifndef SC_NO_CUTPASTE
 	cursor_was_shown = vd->vd_mshown;
@@ -962,20 +971,27 @@
 
 	if (tarea.tr_begin.tp_col < tarea.tr_end.tp_col) {
 		vd->vd_driver->vd_bitblt_text(vd, vw, &tarea);
+		return (1);
 	}
+
+	return (0);
 }
 
 static void
 vt_timer(void *arg)
 {
 	struct vt_device *vd;
+	int changed;
 
 	vd = arg;
 	/* Update screen if required. */
-	vt_flush(vd);
+	changed = vt_flush(vd);
 
 	/* Schedule for next update. */
-	vt_schedule_flush(vd, 0);
+	if (changed)
+		vt_schedule_flush(vd, 0);
+	else
+		vd->vd_timer_armed = 0;
 }
 
 static void
@@ -1286,6 +1302,7 @@
 	if (vd->vd_curwindow == vw) {
 		vt_set_border(vw, vf, TC_BLACK);
 		vd->vd_flags |= VDF_INVALID;
+		vt_resume_flush_timer(vw->vw_device, 0);
 	}
 	vw->vw_flags &= ~VWF_BUSY;
 	VT_UNLOCK(vd);
@@ -1488,7 +1505,7 @@
 		vd->vd_my = y;
 		if ((vd->vd_mstate & MOUSE_BUTTON1DOWN) &&
 		    (vtbuf_set_mark(&vw->vw_buf, VTB_MARK_MOVE,
-			vd->vd_mx / vf->vf_width, 
+			vd->vd_mx / vf->vf_width,
 			vd->vd_my / vf->vf_height) == 1)) {
 
 			/*
@@ -1497,6 +1514,8 @@
 			 */
 			vd->vd_markedwin = vw;
 		}
+
+		vt_resume_flush_timer(vw->vw_device, 0);
 		return; /* Done */
 	case MOUSE_BUTTON_EVENT:
 		/* Buttons */
@@ -1581,6 +1600,7 @@
 		 * window with selection.
 		 */
 		vd->vd_markedwin = vw;
+		vt_resume_flush_timer(vw->vw_device, 0);
 	}
 }
 
@@ -1604,6 +1624,7 @@
 
 	/* Mark mouse position as dirty. */
 	vt_mark_mouse_position_as_dirty(vd);
+	vt_resume_flush_timer(vw->vw_device, 0);
 }
 #endif