diff --git a/src/main.rs b/src/main.rs
index 71d4705..397a40c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2164,9 +2164,23 @@ app.pending_briefing = briefing_of(&campaign, i);
 
         #[cfg(not(target_arch = "wasm32"))]
         let shot_now = shot.as_mut().and_then(|p| p.before_frame(&mut app, &mut ui, &mut menu, &mut r3d, now));
+        #[cfg(not(target_arch = "wasm32"))]
+        let draw_t0 = std::time::Instant::now();
         draw_frame(&mut app, &gfx, &mut r3d, &mut ui, &mut menu, &cloud, &inp, (mx, my), touch_mode, now);
         ui::end_frame();
         #[cfg(not(target_arch = "wasm32"))]
+        if let Some(p) = shot.as_mut() {
+            // the self test reports the time drawing takes (without waiting for the screen)
+            p.frames += 1;
+            p.draw_ms += draw_t0.elapsed().as_secs_f64() * 1000.0;
+            if now - p.report_t >= 2.0 {
+                println!("self test: {:.1} s, {} frames, drawing {:.2} ms per frame, {} units, {} particles", now - p.started.unwrap_or(now), p.frames, p.draw_ms / p.frames.max(1) as f64, app.game.ents.len(), app.game.parts.len());
+                p.frames = 0;
+                p.draw_ms = 0.0;
+                p.report_t = now;
+            }
+        }
+        #[cfg(not(target_arch = "wasm32"))]
         if let Some(path) = shot_now {
             shot_capture(&path);
         }
@@ -2177,7 +2191,8 @@ app.pending_briefing = briefing_of(&campaign, i);
 // ---- self test and screenshots (desktop): DC_SHOT=demo or a savegame file starts it right
 // away, DC_SHOT_STYLE=hd|pixel picks the graphics style (not saved), DC_SHOT_AFTER seconds later
 // (default 10) the screen goes to DC_SHOT_OUT (default /tmp/dc-shot.png) and the game ends;
-// DC_SHOT_ZOOM sets the camera zoom, DC_SHOT_YAW its turn, DC_SHOT_AT=x,z where it looks
+// DC_SHOT_ZOOM sets the camera zoom, DC_SHOT_YAW its turn, DC_SHOT_AT=x,z where it looks;
+// DC_SHOT_FF=seconds runs the game that long at once before (a screen that is off gives few frames)
 #[cfg(not(target_arch = "wasm32"))]
 struct ShotPlan {
     load: String,
@@ -2188,6 +2203,10 @@ struct ShotPlan {
     yaw: Option<f32>,
     at: Option<(f32, f32)>,
     started: Option<f64>,
+    frames: u64,
+    draw_ms: f64,
+    report_t: f64,
+    ff: f32,
 }
 
 #[cfg(not(target_arch = "wasm32"))]
@@ -2207,6 +2226,10 @@ impl ShotPlan {
                 Some((a.trim().parse().ok()?, b.trim().parse().ok()?))
             }),
             started: None,
+            frames: 0,
+            draw_ms: 0.0,
+            report_t: 0.0,
+            ff: num("DC_SHOT_FF").unwrap_or(0.0),
         })
     }
 
@@ -2229,6 +2252,12 @@ impl ShotPlan {
                 }
                 menu.page = None;
                 ui.show_help = false;
+                // fast forward: the game's own steps, without drawing
+                let mut left = self.ff;
+                while left > 0.0 {
+                    app.game.update(0.05);
+                    left -= 0.05;
+                }
                 if let Some(z) = self.zoom {
                     app.cam.zoom = z;
                 }