Performance matrix vs pairs

[latot]

Hi, this is just a tricky question, I would like to know..., if there is a difference between the matrix function and pairs functions, like the shortest path or the distance one. Is there any difference in the performance? I can always do a `` èxpand.grid``` the nodes from a matrix and do it in the pair function, the actual functions (matrix and pair) are helpers to run in a low level function, or they have indeed code to have better performance.

The only thing.., I can think if there is no performance, maybe, is the cost of store the expanded matrix in pairs, some of them can be very heavy in pairs.

Thx!