diff --git a/store/src/board.rs b/store/src/board.rs
index de0e450..0fba2d6 100644
--- a/store/src/board.rs
+++ b/store/src/board.rs
@@ -598,12 +598,40 @@ impl Board {
         core::array::from_fn(|i| i + min)
     }
 
+    /// Returns cumulative white-checker counts: result[i] = # white checkers in fields 1..=i.
+    /// result[0] = 0.
+    pub fn white_checker_cumulative(&self) -> [u8; 25] {
+        let mut cum = [0u8; 25];
+        let mut total = 0u8;
+        for (i, &count) in self.positions.iter().enumerate() {
+            if count > 0 {
+                total += count as u8;
+            }
+            cum[i + 1] = total;
+        }
+        cum
+    }
+
     pub fn move_checker(&mut self, color: &Color, cmove: CheckerMove) -> Result<(), Error> {
         self.remove_checker(color, cmove.from)?;
         self.add_checker(color, cmove.to)?;
         Ok(())
     }
 
+    /// Reverse a previously applied `move_checker`. No validation: assumes the move was valid.
+    pub fn unmove_checker(&mut self, color: &Color, cmove: CheckerMove) {
+        let unit = match color {
+            Color::White => 1,
+            Color::Black => -1,
+        };
+        if cmove.from != 0 {
+            self.positions[cmove.from - 1] += unit;
+        }
+        if cmove.to != 0 {
+            self.positions[cmove.to - 1] -= unit;
+        }
+    }
+
     pub fn remove_checker(&mut self, color: &Color, field: Field) -> Result<(), Error> {
         if field == 0 {
             return Ok(());
diff --git a/store/src/game.rs b/store/src/game.rs
index d32734d..0749040 100644
--- a/store/src/game.rs
+++ b/store/src/game.rs
@@ -156,13 +156,6 @@ impl GameState {
         if let Some(p1) = self.players.get(&1) {
             mirrored_players.insert(2, p1.mirror());
         }
-        let mirrored_history = self
-            .history
-            .clone()
-            .iter()
-            .map(|evt| evt.get_mirror(false))
-            .collect();
-
         let (move1, move2) = self.dice_moves;
         GameState {
             stage: self.stage,
@@ -171,7 +164,7 @@ impl GameState {
             active_player_id: mirrored_active_player,
             // active_player_id: self.active_player_id,
             players: mirrored_players,
-            history: mirrored_history,
+            history: Vec::new(),
             dice: self.dice,
             dice_points: self.dice_points,
             dice_moves: (move1.mirror(), move2.mirror()),
diff --git a/store/src/game_rules_moves.rs b/store/src/game_rules_moves.rs
index 955ab3c..396bcaf 100644
--- a/store/src/game_rules_moves.rs
+++ b/store/src/game_rules_moves.rs
@@ -220,7 +220,7 @@ impl MoveRules {
         // Si possible, les deux dés doivent être joués
         if moves.0.get_from() == 0 || moves.1.get_from() == 0 {
             let mut possible_moves_sequences = self.get_possible_moves_sequences(true, vec![]);
-            possible_moves_sequences.retain(|moves| self.check_exit_rules(moves).is_ok());
+            possible_moves_sequences.retain(|moves| self.check_exit_rules(moves, None).is_ok());
             // possible_moves_sequences.retain(|moves| self.check_corner_rules(moves).is_ok());
             if !possible_moves_sequences.contains(moves) && !possible_moves_sequences.is_empty() {
                 if *moves == (EMPTY_MOVE, EMPTY_MOVE) {
@@ -238,7 +238,7 @@ impl MoveRules {
 
         // check exit rules
         // if !ignored_rules.contains(&TricTracRule::Exit) {
-        self.check_exit_rules(moves)?;
+        self.check_exit_rules(moves, None)?;
         // }
 
         // --- interdit de jouer dans un cadran que l'adversaire peut encore remplir ----
@@ -321,7 +321,11 @@ impl MoveRules {
             .is_empty()
     }
 
-    fn check_exit_rules(&self, moves: &(CheckerMove, CheckerMove)) -> Result<(), MoveError> {
+    fn check_exit_rules(
+        &self,
+        moves: &(CheckerMove, CheckerMove),
+        exit_seqs: Option<&[(CheckerMove, CheckerMove)]>,
+    ) -> Result<(), MoveError> {
         if !moves.0.is_exit() && !moves.1.is_exit() {
             return Ok(());
         }
@@ -331,16 +335,22 @@ impl MoveRules {
         }
 
         // toutes les sorties directes sont autorisées, ainsi que les nombres défaillants
-        let ignored_rules = vec![TricTracRule::Exit];
-        let possible_moves_sequences_without_excedent =
-            self.get_possible_moves_sequences(false, ignored_rules);
-        if possible_moves_sequences_without_excedent.contains(moves) {
+        let owned;
+        let seqs = match exit_seqs {
+            Some(s) => s,
+            None => {
+                owned = self
+                    .get_possible_moves_sequences(false, vec![TricTracRule::Exit]);
+                &owned
+            }
+        };
+        if seqs.contains(moves) {
             return Ok(());
         }
         // À ce stade au moins un des déplacements concerne un nombre en excédant
         // - si d'autres séquences de mouvements sans nombre en excédant sont possibles, on
         // refuse cette séquence
-        if !possible_moves_sequences_without_excedent.is_empty() {
+        if !seqs.is_empty() {
             return Err(MoveError::ExitByEffectPossible);
         }
 
@@ -441,12 +451,18 @@ impl MoveRules {
         } else {
             (dice2, dice1)
         };
+        let filling_seqs = if !ignored_rules.contains(&TricTracRule::MustFillQuarter) {
+            Some(self.get_quarter_filling_moves_sequences())
+        } else {
+            None
+        };
         let mut moves_seqs = self.get_possible_moves_sequences_by_dices(
             dice_max,
             dice_min,
             with_excedents,
             false,
-            ignored_rules.clone(),
+            &ignored_rules,
+            filling_seqs.as_deref(),
         );
         // if we got valid sequences with the highest die, we don't accept sequences using only the
         // lowest die
@@ -456,7 +472,8 @@ impl MoveRules {
             dice_max,
             with_excedents,
             ignore_empty,
-            ignored_rules,
+            &ignored_rules,
+            filling_seqs.as_deref(),
         );
         moves_seqs.append(&mut moves_seqs_order2);
         let empty_removed = moves_seqs
@@ -527,14 +544,16 @@ impl MoveRules {
         let mut moves_seqs = Vec::new();
         let color = &Color::White;
         let ignored_rules = vec![TricTracRule::Exit, TricTracRule::MustFillQuarter];
+        let mut board = self.board.clone();
         for moves in self.get_possible_moves_sequences(true, ignored_rules) {
-            let mut board = self.board.clone();
             board.move_checker(color, moves.0).unwrap();
             board.move_checker(color, moves.1).unwrap();
             // println!("get_quarter_filling_moves_sequences board : {:?}", board);
             if board.any_quarter_filled(*color) && !moves_seqs.contains(&moves) {
                 moves_seqs.push(moves);
             }
+            board.unmove_checker(color, moves.1);
+            board.unmove_checker(color, moves.0);
         }
         moves_seqs
     }
@@ -545,18 +564,27 @@ impl MoveRules {
         dice2: u8,
         with_excedents: bool,
         ignore_empty: bool,
-        ignored_rules: Vec<TricTracRule>,
+        ignored_rules: &[TricTracRule],
+        filling_seqs: Option<&[(CheckerMove, CheckerMove)]>,
     ) -> Vec<(CheckerMove, CheckerMove)> {
         let mut moves_seqs = Vec::new();
         let color = &Color::White;
         let forbid_exits = self.has_checkers_outside_last_quarter();
+        // Precompute non-excedant sequences once so check_exit_rules need not repeat
+        // the full move generation for every exit-move candidate.
+        // Only needed when Exit is not already ignored and exits are actually reachable.
+        let exit_seqs = if !ignored_rules.contains(&TricTracRule::Exit) && !forbid_exits {
+            Some(self.get_possible_moves_sequences(false, vec![TricTracRule::Exit]))
+        } else {
+            None
+        };
+        let mut board = self.board.clone();
         // println!("==== First");
         for first_move in
             self.board
                 .get_possible_moves(*color, dice1, with_excedents, false, forbid_exits)
         {
-            let mut board2 = self.board.clone();
-            if board2.move_checker(color, first_move).is_err() {
+            if board.move_checker(color, first_move).is_err() {
                 println!("err move");
                 continue;
             }
@@ -566,7 +594,7 @@ impl MoveRules {
             let mut has_second_dice_move = false;
             // println!("     ==== Second");
             for second_move in
-                board2.get_possible_moves(*color, dice2, with_excedents, true, forbid_exits)
+                board.get_possible_moves(*color, dice2, with_excedents, true, forbid_exits)
             {
                 if self
                     .check_corner_rules(&(first_move, second_move))
@@ -590,24 +618,10 @@ impl MoveRules {
                         && self.can_take_corner_by_effect())
                     && (ignored_rules.contains(&TricTracRule::Exit)
                         || self
-                            .check_exit_rules(&(first_move, second_move))
-                            // .inspect_err(|e| {
-                            //     println!(
-                            //         " 2nd (exit rule): {:?} - {:?}, {:?}",
-                            //         e, first_move, second_move
-                            //     )
-                            // })
-                            .is_ok())
-                    && (ignored_rules.contains(&TricTracRule::MustFillQuarter)
-                        || self
-                            .check_must_fill_quarter_rule(&(first_move, second_move))
-                            // .inspect_err(|e| {
-                            //     println!(
-                            //         " 2nd: {:?} - {:?}, {:?} for {:?}",
-                            //         e, first_move, second_move, self.board
-                            //     )
-                            // })
+                            .check_exit_rules(&(first_move, second_move), exit_seqs.as_deref())
                             .is_ok())
+                    && filling_seqs
+                        .map_or(true, |seqs| seqs.is_empty() || seqs.contains(&(first_move, second_move)))
                 {
                     if second_move.get_to() == 0
                         && first_move.get_to() == 0
@@ -630,16 +644,14 @@ impl MoveRules {
                 && !(self.is_move_by_puissance(&(first_move, EMPTY_MOVE))
                     && self.can_take_corner_by_effect())
                 && (ignored_rules.contains(&TricTracRule::Exit)
-                    || self.check_exit_rules(&(first_move, EMPTY_MOVE)).is_ok())
-                && (ignored_rules.contains(&TricTracRule::MustFillQuarter)
-                    || self
-                        .check_must_fill_quarter_rule(&(first_move, EMPTY_MOVE))
-                        .is_ok())
+                    || self.check_exit_rules(&(first_move, EMPTY_MOVE), exit_seqs.as_deref()).is_ok())
+                && filling_seqs
+                    .map_or(true, |seqs| seqs.is_empty() || seqs.contains(&(first_move, EMPTY_MOVE)))
             {
                 // empty move
                 moves_seqs.push((first_move, EMPTY_MOVE));
             }
-            //if board2.get_color_fields(*color).is_empty() {
+            board.unmove_checker(color, first_move);
         }
         moves_seqs
     }
@@ -1498,6 +1510,7 @@ mod tests {
             CheckerMove::new(23, 0).unwrap(),
             CheckerMove::new(24, 0).unwrap(),
         );
+        let filling_seqs = Some(state.get_quarter_filling_moves_sequences());
         assert_eq!(
             vec![moves],
             state.get_possible_moves_sequences_by_dices(
@@ -1505,7 +1518,8 @@ mod tests {
                 state.dice.values.1,
                 true,
                 false,
-                vec![]
+                &[],
+                filling_seqs.as_deref(),
             )
         );
 
@@ -1520,6 +1534,7 @@ mod tests {
             CheckerMove::new(19, 23).unwrap(),
             CheckerMove::new(22, 0).unwrap(),
         )];
+        let filling_seqs = Some(state.get_quarter_filling_moves_sequences());
         assert_eq!(
             moves,
             state.get_possible_moves_sequences_by_dices(
@@ -1527,7 +1542,8 @@ mod tests {
                 state.dice.values.1,
                 true,
                 false,
-                vec![]
+                &[],
+                filling_seqs.as_deref(),
             )
         );
         let moves = vec![(
@@ -1541,7 +1557,8 @@ mod tests {
                 state.dice.values.0,
                 true,
                 false,
-                vec![]
+                &[],
+                filling_seqs.as_deref(),
             )
         );
 
@@ -1557,6 +1574,7 @@ mod tests {
             CheckerMove::new(19, 21).unwrap(),
             CheckerMove::new(23, 0).unwrap(),
         );
+        let filling_seqs = Some(state.get_quarter_filling_moves_sequences());
         assert_eq!(
             vec![moves],
             state.get_possible_moves_sequences_by_dices(
@@ -1564,7 +1582,8 @@ mod tests {
                 state.dice.values.1,
                 true,
                 false,
-                vec![]
+                &[],
+                filling_seqs.as_deref(),
             )
         );
     }
@@ -1583,13 +1602,13 @@ mod tests {
             CheckerMove::new(19, 23).unwrap(),
             CheckerMove::new(22, 0).unwrap(),
         );
-        assert!(state.check_exit_rules(&moves).is_ok());
+        assert!(state.check_exit_rules(&moves, None).is_ok());
 
         let moves = (
             CheckerMove::new(19, 24).unwrap(),
             CheckerMove::new(22, 0).unwrap(),
         );
-        assert!(state.check_exit_rules(&moves).is_ok());
+        assert!(state.check_exit_rules(&moves, None).is_ok());
 
         state.dice.values = (6, 4);
         state.board.set_positions(
@@ -1602,7 +1621,7 @@ mod tests {
             CheckerMove::new(20, 24).unwrap(),
             CheckerMove::new(23, 0).unwrap(),
         );
-        assert!(state.check_exit_rules(&moves).is_ok());
+        assert!(state.check_exit_rules(&moves, None).is_ok());
     }
 
     #[test]
diff --git a/store/src/training_common.rs b/store/src/training_common.rs
index 57094a9..6a5b537 100644
--- a/store/src/training_common.rs
+++ b/store/src/training_common.rs
@@ -3,7 +3,6 @@
 use std::cmp::{max, min};
 use std::fmt::{Debug, Display, Formatter};
 
-use crate::board::Board;
 use crate::{CheckerMove, Dice, GameEvent, GameState};
 use serde::{Deserialize, Serialize};
 
@@ -221,10 +220,11 @@ pub fn get_valid_actions(game_state: &GameState) -> anyhow::Result<Vec<TrictracA
                 // Ajoute aussi les mouvements possibles
                 let rules = crate::MoveRules::new(&color, &game_state.board, game_state.dice);
                 let possible_moves = rules.get_possible_moves_sequences(true, vec![]);
-
+                // rules.board is already White-perspective (mirrored if Black): compute cum once.
+                let cum = rules.board.white_checker_cumulative();
                 for (move1, move2) in possible_moves {
-                    valid_actions.push(checker_moves_to_trictrac_action(
-                        &move1, &move2, &color, game_state,
+                    valid_actions.push(white_checker_moves_to_trictrac_action(
+                        &move1, &move2, &game_state.dice, &cum,
                     )?);
                 }
             }
@@ -235,10 +235,11 @@ pub fn get_valid_actions(game_state: &GameState) -> anyhow::Result<Vec<TrictracA
                     // Empty move
                     possible_moves.push((CheckerMove::default(), CheckerMove::default()));
                 }
-
+                // rules.board is already White-perspective (mirrored if Black): compute cum once.
+                let cum = rules.board.white_checker_cumulative();
                 for (move1, move2) in possible_moves {
-                    valid_actions.push(checker_moves_to_trictrac_action(
-                        &move1, &move2, &color, game_state,
+                    valid_actions.push(white_checker_moves_to_trictrac_action(
+                        &move1, &move2, &game_state.dice, &cum,
                     )?);
                 }
             }
@@ -251,36 +252,27 @@ pub fn get_valid_actions(game_state: &GameState) -> anyhow::Result<Vec<TrictracA
     Ok(valid_actions)
 }
 
+#[cfg(test)]
 fn checker_moves_to_trictrac_action(
     move1: &CheckerMove,
     move2: &CheckerMove,
     color: &crate::Color,
     state: &GameState,
 ) -> anyhow::Result<TrictracAction> {
-    let dice = &state.dice;
-    let board = &state.board;
-
-    if color == &crate::Color::Black {
-        // Moves are already 'white', so we don't mirror them
-        white_checker_moves_to_trictrac_action(
-            move1,
-            move2,
-            // &move1.clone().mirror(),
-            // &move2.clone().mirror(),
-            dice,
-            &board.clone().mirror(),
-        )
-        // .map(|a| a.mirror())
+    // Moves are always in White's coordinate system. For Black, mirror the board first.
+    let cum = if color == &crate::Color::Black {
+        state.board.mirror().white_checker_cumulative()
     } else {
-        white_checker_moves_to_trictrac_action(move1, move2, dice, board)
-    }
+        state.board.white_checker_cumulative()
+    };
+    white_checker_moves_to_trictrac_action(move1, move2, &state.dice, &cum)
 }
 
 fn white_checker_moves_to_trictrac_action(
     move1: &CheckerMove,
     move2: &CheckerMove,
     dice: &Dice,
-    board: &Board,
+    cum: &[u8; 25],
 ) -> anyhow::Result<TrictracAction> {
     let to1 = move1.get_to();
     let to2 = move2.get_to();
@@ -321,11 +313,21 @@ fn white_checker_moves_to_trictrac_action(
     }
     let dice_order = diff_move1 == dice.values.0 as usize;
 
-    let checker1 = board.get_field_checker(&crate::Color::White, from1) as usize;
-    let mut tmp_board = board.clone();
-    // should not raise an error for a valid action
-    tmp_board.move_checker(&crate::Color::White, *move1)?;
-    let checker2 = tmp_board.get_field_checker(&crate::Color::White, from2) as usize;
+    // cum[i] = # white checkers in fields 1..=i (precomputed by the caller).
+    // checker1 is the ordinal of the last checker at from1.
+    let checker1 = cum[from1] as usize;
+    // checker2 is the ordinal on the board after move1 (removed from from1, added to to1).
+    // Adjust the cumulative in O(1) without cloning the board.
+    let checker2 = {
+        let mut c = cum[from2];
+        if from1 > 0 && from2 >= from1 {
+            c -= 1; // one checker was removed from from1, shifting later ordinals down
+        }
+        if from1 > 0 && to1 > 0 && from2 >= to1 {
+            c += 1; // one checker was added at to1, shifting later ordinals up
+        }
+        c as usize
+    };
     Ok(TrictracAction::Move {
         dice_order,
         checker1,