Should I cache variables instead of creating them every time as method variables?

Questions & Answers
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1

I am just starting to get a hand on memory management, and this question I haven’t luck yet to find be answered clearly.
So in short, which implementation is better to produce less garbadge and optionally be more performant:

public class Damager: MonoBehaviour
{
private float dps = 1;
void Update()
{
        if(Physics.Raycast(transform.position, transform.forward, out RaycastHit hit))
        {
            Idamagable target = hit.collider.gameObject.GetComponent<Idamagable>();
            if (target != null)
            {
                target.getDamage(dps * Time.deltaTime);
            }
        }
}

Or

public class Damager: MonoBehaviour
{
private float dps = 1;
private Idamagable cachedtarget;
private RaycastHit cachedhit;
void Update()
{
        if(Physics.Raycast(transform.position, transform.forward, out cachedhit))
        {
            cachedtarget = cachedhit.collider.gameObject.GetComponent<Idamagable>();
            if (cachedtarget != null)
            {
                cachedtarget.getDamage(dps * Time.deltaTime);
            }
        }
}
2

When declared inline the value of the RaycastHit instance and the reference to the Idamagable component is allocated on the stack, so it’s practically free. Unless you want to use the contents of the variable later, don’t declare it in the class.

The second version would allocate slightly more space when the Damager class is allocated, but it’s such a non-issue that it’d be fine if you needed to do that.