diff --git a/src/components/drug.cairo b/src/components/drug.cairo
index 503ed6575..678d547f7 100644
--- a/src/components/drug.cairo
+++ b/src/components/drug.cairo
@@ -13,10 +13,7 @@ struct Drug {
     quantity: usize,
 }
 
-trait DrugTrait {
-    fn all() -> Span<felt252>;
-}
-
+#[generate_trait]
 impl DrugImpl of DrugTrait {
     fn all() -> Span<felt252> {
         let mut drugs = array::ArrayTrait::new();
diff --git a/src/components/game.cairo b/src/components/game.cairo
index 990bf977d..b13222e8d 100644
--- a/src/components/game.cairo
+++ b/src/components/game.cairo
@@ -14,19 +14,16 @@ struct Game {
     creator: ContractAddress,
 }
 
-
-trait GameTrait {
-    fn tick(self: @Game) -> bool;
-}
-
+#[generate_trait]
 impl GameImpl of GameTrait {
-    fn tick(self: @Game) -> bool {
+    #[inline(always)]
+    fn tick(self: Game) -> bool {
         let info = starknet::get_block_info().unbox();
 
-        if info.block_timestamp < *self.start_time {
+        if info.block_timestamp < self.start_time {
             return false;
         }
-        if *self.is_finished {
+        if self.is_finished {
             return false;
         }
 
diff --git a/src/components/location.cairo b/src/components/location.cairo
index c4d956b0a..dd6937ead 100644
--- a/src/components/location.cairo
+++ b/src/components/location.cairo
@@ -5,11 +5,7 @@ use starknet::ContractAddress;
 
 struct Location {}
 
-trait LocationTrait {
-    fn all() -> Span<felt252>;
-    fn random(seed: felt252) -> felt252;
-}
-
+#[generate_trait]
 impl LocationImpl of LocationTrait {
     fn all() -> Span<felt252> {
         let mut locations = array::ArrayTrait::new();
diff --git a/src/components/market.cairo b/src/components/market.cairo
index 7874cb55b..4e436180b 100644
--- a/src/components/market.cairo
+++ b/src/components/market.cairo
@@ -16,21 +16,19 @@ struct Market {
     quantity: usize,
 }
 
-trait MarketTrait {
-    fn buy(self: @Market, quantity: usize) -> u128;
-    fn sell(self: @Market, quantity: usize) -> u128;
-}
-
+#[generate_trait]
 impl MarketImpl of MarketTrait {
-    fn buy(self: @Market, quantity: usize) -> u128 {
-        assert(quantity < *self.quantity, 'not enough liquidity');
+    #[inline(always)]
+    fn buy(ref self: Market, quantity: usize) -> u128 {
+        assert(quantity < self.quantity, 'not enough liquidity');
         let (amount, available, cash) = normalize(quantity, self);
         let k = cash * available;
         let cost = (k / (available - amount)) - cash;
         cost
     }
 
-    fn sell(self: @Market, quantity: usize) -> u128 {
+    #[inline(always)]
+    fn sell(ref self: Market, quantity: usize) -> u128 {
         let (amount, available, cash) = normalize(quantity, self);
         let k = cash * available;
         let payout = cash - (k / (available + amount));
@@ -38,17 +36,17 @@ impl MarketImpl of MarketTrait {
     }
 }
 
-fn normalize(amount: usize, market: @Market) -> (u128, u128, u128) {
+fn normalize(amount: usize, market: Market) -> (u128, u128, u128) {
     let amount: u128 = amount.into() * SCALING_FACTOR;
-    let available: u128 = (*market.quantity).into() * SCALING_FACTOR;
-    (amount, available, *market.cash)
+    let available: u128 = (market.quantity).into() * SCALING_FACTOR;
+    (amount, available, market.cash)
 }
 
 
 #[test]
 #[should_panic(expected: ('not enough liquidity', ))]
 fn test_not_enough_quantity() {
-    let market = Market {
+    let mut market = Market {
         game_id: 0, location_id: 0, drug_id: 0, cash: SCALING_FACTOR * 1, quantity: 1
     }; // pool 1:1
     let cost = market.buy(10);
@@ -57,7 +55,7 @@ fn test_not_enough_quantity() {
 #[test]
 #[available_gas(100000)]
 fn test_market_buy() {
-    let market = Market {
+    let mut market = Market {
         game_id: 0, location_id: 0, drug_id: 0, cash: SCALING_FACTOR * 1, quantity: 10
     }; // pool 1:10
     let cost = market.buy(5);
@@ -67,7 +65,7 @@ fn test_market_buy() {
 #[test]
 #[available_gas(100000)]
 fn test_market_sell() {
-    let market = Market {
+    let mut market = Market {
         game_id: 0, location_id: 0, drug_id: 0, cash: SCALING_FACTOR * 1, quantity: 10
     }; // pool 1:10
     let payout = market.sell(5);
diff --git a/src/components/player.cairo b/src/components/player.cairo
index 62a962aea..69b706411 100644
--- a/src/components/player.cairo
+++ b/src/components/player.cairo
@@ -12,16 +12,14 @@ struct Player {
     turns_remaining: usize,
 }
 
-trait PlayerTrait {
-    fn can_continue(self: @Player) -> bool;
-}
-
+#[generate_trait]
 impl PlayerImpl of PlayerTrait {
-    fn can_continue(self: @Player) -> bool {
-        if *self.health == 0 {
+    #[inline(always)]
+    fn can_continue(ref self: Player) -> bool {
+        if self.health == 0 {
             return false;
         }
-        if *self.turns_remaining == 0 {
+        if self.turns_remaining == 0 {
             return false;
         }
 
diff --git a/src/components/risks.cairo b/src/components/risks.cairo
index 371494574..e58486940 100644
--- a/src/components/risks.cairo
+++ b/src/components/risks.cairo
@@ -17,26 +17,23 @@ struct Risks {
     game_id: u32,
     #[key]
     location_id: felt252,
-    // travel risk probabilities
     travel: u8,
     hurt: u8,
     mugged: u8,
     arrested: u8,
 }
 
-trait RisksTrait {
-    fn travel(self: @Risks, seed: felt252) -> (bool, TravelResult);
-}
-
+#[generate_trait]
 impl RisksImpl of RisksTrait {
-    fn travel(self: @Risks, seed: felt252) -> (bool, TravelResult) {
+    #[inline(always)]
+    fn travel(ref self: Risks, seed: felt252) -> (bool, TravelResult) {
         let mut seed = seed;
         let mut health_loss = 0;
         let mut arrested = false;
         let mut mugged = false;
         let mut event_occured = false;
 
-        if occurs(seed, *self.travel) {
+        if occurs(seed, self.travel) {
             seed = pedersen::pedersen(seed, seed);
             event_occured = true;
 
@@ -58,7 +55,7 @@ fn occurs(seed: felt252, likelihood: u8) -> bool {
 #[available_gas(1000000)]
 fn test_never_occurs() {
     let seed = pedersen::pedersen(1, 1);
-    let risks = Risks { game_id: 0, location_id: 0, travel: 0, hurt: 0, mugged: 0, arrested: 0,  };
+    let mut risks = Risks { game_id: 0, location_id: 0, travel: 0, hurt: 0, mugged: 0, arrested: 0,  };
     let (event_occured, result) = risks.travel(seed);
 
     assert(!event_occured, 'event occured');
@@ -71,7 +68,7 @@ fn test_never_occurs() {
 #[available_gas(1000000)]
 fn test_always_occurs() {
     let seed = pedersen::pedersen(1, 1);
-    let risks = Risks {
+    let mut risks = Risks {
         game_id: 0, location_id: 0, travel: 100, hurt: 100, mugged: 100, arrested: 100, 
     };
     let (event_occured, result) = risks.travel(seed);
diff --git a/src/systems/trade.cairo b/src/systems/trade.cairo
index 5c59b1ed3..e328b624f 100644
--- a/src/systems/trade.cairo
+++ b/src/systems/trade.cairo
@@ -9,7 +9,7 @@ mod buy {
 
     use rollyourown::components::name::Name;
     use rollyourown::components::drug::Drug;
-    use rollyourown::components::player::Player;
+    use rollyourown::components::player::{Player, PlayerTrait};
     use rollyourown::components::location::Location;
     use rollyourown::components::game::{Game, GameTrait};
     use rollyourown::components::risks::{Risks, RisksTrait};
@@ -45,6 +45,7 @@ mod buy {
 
         let mut player = get!(ctx.world, (game_id, player_id).into(), Player);
         assert(player.location_id == location_id, 'player is not at location');
+        assert(player.can_continue(), 'player cannot trade');
 
         let mut market = get!(ctx.world, (game_id, location_id, drug_id).into(), Market);
 
diff --git a/src/systems/travel.cairo b/src/systems/travel.cairo
index 2bcb4c33f..5757f50c9 100644
--- a/src/systems/travel.cairo
+++ b/src/systems/travel.cairo
@@ -47,10 +47,10 @@ mod travel {
 
         let player_id = ctx.origin;
         let mut player = get!(ctx.world, (game_id, player_id).into(), Player);
-        assert(player.can_continue(), 'player cannot continue');
+        assert(player.can_continue(), 'player cannot travel');
         assert(player.location_id != next_location_id, 'already at location');
 
-        let risks = get!(ctx.world, (game_id, next_location_id).into(), Risks);
+        let mut risks = get!(ctx.world, (game_id, next_location_id).into(), Risks);
         let seed = starknet::get_tx_info().unbox().transaction_hash;
 
         let (event_occured, result) = risks.travel(seed);