A* will give us the way from the start point to the end across other nodes. but if the distances between the nodes are small the path will be bad. (i.e. the player will move like the warm ). i do smoothing the path by an expensive algo (high costed time). what the way to less the time cost of the Path Smoothing? Thanks advanced

There is an article about path smoothing at gamasutra called 'Toward More Realistic Pathfinding'.