Accessing value from dict allocates 28 bytes

Hi,

In short, reading and storing the value of a dictionary seems to allocate 28 bytes each time. I was wondering if there was a way around it.

If you're familiar with A* pathfinding, this is the portion that finds the minimum F score amongst the available 'potential future locations' in the open set. The problematic line is:

 tempf=infscore[entry];

Because this line is called so often, It's accruing more than 10MB of garbage per frame. Full code of the function is here:

 Vector3 minv3(HashSet<Vector3> inopen, Dictionary<Vector3,float> infscore){
         float minval = Mathf.Infinity;
         float tempf = new float ();
         Vector3 retminv3 = new Vector3 ();
         foreach(Vector3 entry in inopen){
             tempf=infscore[entry];
             if (tempf<minval){
                 minval=tempf;
                 retminv3=entry;
             }
         }
         return retminv3;
     }

Any help would be much appreciated.

Thanks.