[Entitas:] Remove entity cache in group.GetEntities()

… and return the internal HasSet as IEnumerable to avoid memory alloc when group changes often.

Alternatively, make group enumerable like

// look closely: no group.GetEntities() call
foreach (var e in group) {
    // ...
}

[ghost]

Something tells me you’re really into optimization @optimisez 😉

[rastlin86]

AddRange always creates a new array internally regardless if the list needs to be resized or not, at leas in Microsoft implementation:

https://stackoverflow.com/questions/2123161/listt-addrange-implementation-suboptimal

Have not tested that, but I’m like 80% sure this is also the way it’s implemented in mono.