Fix loading times

server/main.py

@@ -1,3 +1,4 @@
+from contextlib import asynccontextmanager
 from pathlib import Path
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
@@ -5,7 +6,16 @@ from fastapi.staticfiles import StaticFiles
 
 from server.routes import hexagons
 
-app = FastAPI(title="Property Map API")
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    # Startup: preload all parquet files
+    hexagons.preload_dataframes()
+    yield
+    # Shutdown: nothing to clean up
+
+
+app = FastAPI(title="Property Map API", lifespan=lifespan)
 
 app.add_middleware(
     CORSMiddleware,