keyfork-qrcode: add framerate tracker

crates/qrcode/keyfork-qrcode/src/lib.rs

@@ -170,6 +170,8 @@ fn dbg_elapsed(count: u64, instant: Instant) {
     let elapsed = instant.elapsed().as_secs();
     let framerate = count as f64 / elapsed as f64;
     eprintln!("framerate: {count}/{elapsed} = {framerate}");
+    std::thread::sleep(std::time::Duration::from_secs(5));
+
 }
 
 #[derive(Debug)]