One of the Disadvantages of the Get Component approach is that it has poor performance because it searches for the component every frame, so the obvious way to avoid that issue is to search only once on startup and store a reference to the other component so you can use it without searching again.

using UnityEngine;

public sealed class GetComponentCachedExample : MonoBehaviour
{
    private Rigidbody _Rigidbody;

    private void Awake()
    {
        _Rigidbody = GetComponent<Rigidbody>();
    }

    private void FixedUpdate()
    {
        _Rigidbody.AddForce(Vector3.up * 10);
    }
}

Needing to specify the Rigidbody type for both the field and the GetComponent call is not ideal, and fortunately it can be easily avoided by using TryGetComponent instead:

        // Replace this:
        _Rigidbody = GetComponent<Rigidbody>();

        // With this:
        TryGetComponent(out _Rigidbody);

        // Because the compiler already knows the type of '_Rigidbody' so you don't need to do:
        TryGetComponent<Rigidbody>(out _Rigidbody);

This allows the code to be a bit shorter, but more importantly it also means that if you decide to change the field's type to something else (such as a CharacterController), you only have to modify the field and the TryGetComponent will automatically infer the new type. This reduces the number of other things you need to fix when changing this part of your code, which is good for productivity.

Advantages

• Better performance than the Get Component approach.

Disadvantages