Movement.cs

using UnityEngine;
using UnityEngine.AI;

public class Movement : MonoBehaviour
{
    [SerializeField]
    private Camera camera;

    private string groundTag = "Ground";

    private NavMeshAgent agent;

    private RaycastHit hit;

    // Called when a script is enabled
    void Start()
    {
        agent = GetComponent<NavMeshAgent>();
    }

    // Called once every frame
    void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            Ray ray = camera.ScreenPointToRay(Input.mousePosition);

            if (Physics.Raycast(ray, out hit, Mathf.Infinity))
            {
                if (hit.collider.CompareTag(groundTag)) 
                {
                    agent.SetDestination(hit.point);
                }
            }
        }
    }
}

Is there a way to increase the speed of the ray cast?

Hi @Tydoubleyou-pixel. I'm not sure what you mean by the speed of the raycast. A raycast is just a check from an origin (fx Vector3(0, 0, 0)) towards some direction (fx Vector3(0, 0, 1)) and a length (fx 1). Speed is not a parameter you can pass to the method. You can read about the options of raycast here: https://docs.unity3d.com/ScriptReference/Physics.Raycast.html

If you mean the travel speed of movement from the original position to raycasted MousePosition then you adjust the agent speed in the inspector