---
title: "Performance & Composition"
description: "Watch session resolution time, enable session caching, wire the standalone Nitro hook, and combine with the AI SDK integration."
canonical_url: "https://www.evlog.dev/use-cases/better-auth/performance"
---
# Performance & Composition

> Watch session resolution time, enable session caching, wire the standalone Nitro hook, and combine with the AI SDK integration.

`getSession()` costs a database query on every request. The integration measures it for you and exposes the timing as `auth.resolvedIn` so you can spot regressions before users do.

## Watch session resolution time

```json [Wide Event — slow session resolution]
{
  "auth": { "resolvedIn": 245, "identified": true },
  "duration": "312ms"
}
```

When `auth.resolvedIn` is high relative to `duration`, your auth backend is the bottleneck.

## Tune for high traffic

1. **Enable cookie caching** in Better Auth so session lookups don't hit the database every time.
2. **Use exclude** on `createAuthMiddleware` to skip public routes that don't need user context.
3. **Use include** to limit resolution to specific route patterns instead of the entire app.

A common P95 target after caching: `auth.resolvedIn < 5ms`.

## Standalone Nitro

`createAuthIdentifier` is a factory that creates a Nitro `request` hook. Designed for **standalone Nitro** apps where the evlog Nitro module handles hook ordering.

<note>

For **Nuxt**, use `createAuthMiddleware` in a server middleware instead, because Nitro plugin hook ordering can cause the logger to not be available yet in the `request` hook.

</note>

```typescript [server/plugins/evlog-auth.ts]
import { createAuthIdentifier } from 'evlog/better-auth'
import { auth } from './lib/auth'

export default defineNitroPlugin((nitroApp) => {
  nitroApp.hooks.hook('request', createAuthIdentifier(auth, {
    exclude: ['/api/auth/**', '/api/public/**'],
  }))
})
```

It accepts the same options as [`createAuthMiddleware`](https://www.evlog.dev/use-cases/better-auth/middleware#options).

## Combine with the AI SDK

When you also use [`evlog/ai`](https://www.evlog.dev/use-cases/ai-sdk/overview), your wide events include both user identity **and** AI metrics in a single event:

```json [Wide Event — AI + User]
{
  "method": "POST",
  "path": "/api/chat",
  "status": 200,
  "duration": "4.5s",
  "durationMs": 4512,
  "userId": "QBX9tPjJQExWawAbNll75",
  "user": {
    "id": "QBX9tPjJQExWawAbNll75",
    "name": "Hugo Richard",
    "email": "hugo@example.com"
  },
  "auth": { "resolvedIn": 8, "identified": true },
  "ai": {
    "calls": 1,
    "model": "claude-sonnet-4.6",
    "provider": "anthropic",
    "inputTokens": 3312,
    "outputTokens": 814,
    "totalTokens": 4126,
    "msToFirstChunk": 234,
    "msToFinish": 4500,
    "tokensPerSecond": 180
  }
}
```

This is what a wide event buys you: one event per request, all context in one place: who made the request, what they did, how the AI responded, and how it performed.

---

- [Middleware](https://www.evlog.dev/use-cases/better-auth/middleware)
- [AI SDK](https://www.evlog.dev/use-cases/ai-sdk/overview)


## Sitemap

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