What your application actually does
When your application handles a request that involves AI, here’s what happens: 1. Receive request and authenticate (CPU)2. Validate input and check business rules (CPU)
3. Fetch relevant data from your database (CPU)
4. Transform data into the format your model expects (CPU)
5. Run inference (CPU or GPU)
6. Apply business logic to the prediction (CPU)
7. Update database, trigger workflows (CPU)
8. Format and return response (CPU)
Step 5 - running inference - is the only place a GPU might matter. Everything else is standard application logic that runs on CPU.
When your application needs GPU infrastructure
Most applications don’t. GPU infrastructure makes sense in specific scenarios:- You’re using massive Generative models: If you’ve chosen to self-host large transformer models (i.e. LLMs) rather than using an API (such as OpenAI, Anthropic, etc).
- Your application serves extreme volumes: If you handle thousands of AI-powered requests per second and can batch them, a GPU’s throughput can be more cost-effective than a massive fleet of CPU instances.
- You’re training or fine-tuning: If your application includes a training pipeline (retraining models on user data) that’s where GPUs are essential.
Why CPU infrastructure works for most applications
You’re deploying an application, not a model: Your application needs databases, caching, background jobs, API endpoints. Adding AI inference is one more feature, not a reason to redesign your entire infrastructure. If you can run inference on the same instances that handle your API traffic, your deployment stays simple. Production-ready models run on CPUs: Models optimised for production use run efficiently on modern CPUs. DistilBERT for language tasks, MobileNet for image classification, XGBoost for structured data. These aren’t toy models; they power real applications at scale. Even large models can work fine if your use case allows slower inference. Background jobs, async workflow and batch processing don’t need millisecond response times. Match your infrastructure to your actual requirements. Your application traffic probably doesn’t justify GPU cost: Unless you’re serving thousands of AI requests per second, the cost of GPU infrastructure exceeds the cost of running inference on CPU. CPUs scale naturally with your application traffic. GPUs require sustained high utilisation to justify their cost. Infrastructure complexity matters: CPU-only deployment means your team uses the tools and workflows they already know. Standard containers, familiar debugging, local development without special hardware. No GPU drivers, no CUDA versions, no specialised orchestration. For teams building applications, this is significant.Architecting AI into your application
You have two deployment patterns: Monolithic (simpler): Run inference in your application backend alongside your other logic. Your API servers handle HTTP requests, database queries, business logic, and AI inference. Everything runs on CPU instances. This works well for most applications and keeps deployment straightforward. Separated (more flexible): Run your application on CPU instances and call a separate model serving layer for inference. That serving layer can be CPU or GPU depending on your needs. This pattern makes sense when you have multiple applications sharing models, or when inference requirements differ significantly from your application’s requirements. Start with the monolithic pattern. If you outgrow it, migrate to separated serving. The migration is easier than starting with complex infrastructure you don’t need yet.Making the decision for your application
The default is CPU-based deployment. Move to GPU only when you have measured evidence that you need it. Deploy on CPU when (most applications):- Building an application with AI features, not an AI-first product
- Using models designed for production deployment
- Application serves typical web/API traffic patterns
- Team uses standard deployment workflows
- Getting to production quickly matters
- Your application is only using the openai API
- Measured CPU inference latency violates your SLAs after trying optimised models
- Application consistently serves thousands of AI requests per second
- Cost analysis shows GPU infrastructure is more economical at your scale
- You’ve already optimised everything else and inference is the bottleneck