diff --git a/main.py b/main.py
index b13cdd1..b418ded 100644
--- a/main.py
+++ b/main.py
@@ -9,8 +9,8 @@ import signal
 import queue
 
 latest_book = {'bids': [], 'asks': [], 'timestamp': None}
-book_history = deque()
-trade_history = deque()
+book_history = deque(maxlen=200)  # Keep last 100 book updates (~20-60 seconds)
+trade_history = deque(maxlen=500)  # Keep last 1000 trades (~2-10 minutes)
 
 TRADE_HISTORY_SECONDS = 60
 BOOK_HISTORY_SECONDS = 5