Improving Nginx performance with worker_processes involves configuring this directive appropriately based on your server's hardware resources and workload.
Here's a guide on how to do it:

Understand worker_processes: The worker_processes directive in the Nginx configuration file (nginx.conf) defines how many worker processes Nginx should spawn to handle incoming connections. Each worker process is essentially a single-threaded instance of Nginx.

Determine available CPU cores: First, determine how many CPU cores are available on your server. You typically want to have one worker process per CPU core. However, you may need to adjust this based on your server's workload and available resources.

Calculate optimal value: Once you know the number of CPU cores, set the worker_processes directive in your Nginx configuration file. The formula to calculate the optimal value is usually worker_processes = number of CPU cores.

Consider hyperthreading: If your CPU supports hyperthreading, you might have twice as many "logical" cores as physical cores. In such cases, you might consider setting worker_processes to twice the number of physical cores.

Monitor performance: After making changes, monitor your server's performance to ensure that it's handling the workload efficiently. Tools like top, htop, or Nginx's built-in monitoring tools can help you track resource usage and performance metrics.

Adjust as needed: If you notice performance issues or inefficiencies, you may need to adjust the worker_processes value accordingly. For example, if your server is handling a particularly heavy workload, you might increase the number of worker processes slightly.

Consider other factors: Keep in mind that worker_processes is just one factor affecting Nginx performance. Other directives such as worker_connections, keepalive_timeout, and multi_accept can also impact performance and should be configured appropriately based on your server's requirements.

Here's an example of how you might set worker_processes in your nginx.conf file:

worker_processes auto; # automatically detect the number of CPU cores

Or, if you want to specify the number of worker processes manually:
worker_processes 4; # for a server with 4 CPU cores

Remember to reload or restart Nginx after making changes to the configuration file for them to take effect:
sudo systemctl reload nginx

By optimizing the worker_processes directive, you can ensure that Nginx efficiently utilizes your server's resources to handle incoming connections and improve overall performance.