diff --git a/server/src/__tests__/auth-middleware.test.ts b/server/src/__tests__/auth-middleware.test.ts
new file mode 100644
index 00000000000..890d1cb8205
--- /dev/null
+++ b/server/src/__tests__/auth-middleware.test.ts
@@ -0,0 +1,43 @@
+import { describe, expect, it, vi } from "vitest";
+import express from "express";
+import request from "supertest";
+import { actorMiddleware } from "../middleware/auth.js";
+
+function createApp(resolveSession: ReturnType<typeof vi.fn>) {
+  const app = express();
+  app.use(
+    actorMiddleware({} as never, {
+      deploymentMode: "authenticated",
+      resolveSession,
+    }),
+  );
+  app.get("/", (_req, res) => {
+    res.status(200).send("ok");
+  });
+  app.get("/api/ping", (_req, res) => {
+    res.status(200).json({ ok: true });
+  });
+  return app;
+}
+
+describe("actorMiddleware", () => {
+  it("skips session resolution for non-api page requests", async () => {
+    const resolveSession = vi.fn(async () => null);
+    const app = createApp(resolveSession);
+
+    const res = await request(app).get("/");
+
+    expect(res.status).toBe(200);
+    expect(resolveSession).not.toHaveBeenCalled();
+  });
+
+  it("still resolves sessions for api requests", async () => {
+    const resolveSession = vi.fn(async () => null);
+    const app = createApp(resolveSession);
+
+    const res = await request(app).get("/api/ping");
+
+    expect(res.status).toBe(200);
+    expect(resolveSession).toHaveBeenCalledOnce();
+  });
+});
diff --git a/server/src/middleware/auth.ts b/server/src/middleware/auth.ts
index 6140c87d5b5..5f0cef802d8 100644
--- a/server/src/middleware/auth.ts
+++ b/server/src/middleware/auth.ts
@@ -18,6 +18,13 @@ interface ActorMiddlewareOptions {
   resolveSession?: (req: Request) => Promise<BetterAuthSessionResult | null>;
 }
 
+function shouldResolveBoardSession(req: Request): boolean {
+  // Only API routes consume req.actor. Skipping session resolution for
+  // document/static requests avoids unnecessary Better Auth work on each
+  // Vite-served page load in authenticated dev mode.
+  return req.path.startsWith("/api");
+}
+
 export function actorMiddleware(db: Db, opts: ActorMiddlewareOptions): RequestHandler {
   const boardAuth = boardAuthService(db);
   return async (req, _res, next) => {
@@ -30,7 +37,11 @@ export function actorMiddleware(db: Db, opts: ActorMiddlewareOptions): RequestHa
 
     const authHeader = req.header("authorization");
     if (!authHeader?.toLowerCase().startsWith("bearer ")) {
-      if (opts.deploymentMode === "authenticated" && opts.resolveSession) {
+      if (
+        opts.deploymentMode === "authenticated" &&
+        opts.resolveSession &&
+        shouldResolveBoardSession(req)
+      ) {
         let session: BetterAuthSessionResult | null = null;
         try {
           session = await opts.resolveSession(req);