again, some minor perf improvement, probably be the last

simu/src/main.rs

@@ -300,6 +300,8 @@ fn main() -> Result<(), Error> {
             loop {
                 simulation.step(64);
             }
+
+            //ugly debug code, I should improve that using a real TUI crate
             #[cfg(feature = "debug")]
             {
                 let mut input = std::io::stdin().lines();