If used for larger games, one cannot afford to examine the whole tree. The solution is to stop at some search depth and then estimate how good the position is with some heuristic.
One common optimization is alpha-beta pruning. It is applicable of you have already found a good move (when we use a heuristic we don't know for sure if it will win or not, only if it is good or not), and consider another candidate move. If the latter move has a strong counter, that means it will for sure be worse than the good move. We can then immediately discard the weak move from consideration, there is no need to find out just how weak it is. To make best use of this, one should check promising moves first, because then the bar for potential moves will be higher and more pruning can be done.
One common optimization is alpha-beta pruning. It is applicable of you have already found a good move (when we use a heuristic we don't know for sure if it will win or not, only if it is good or not), and consider another candidate move. If the latter move has a strong counter, that means it will for sure be worse than the good move. We can then immediately discard the weak move from consideration, there is no need to find out just how weak it is. To make best use of this, one should check promising moves first, because then the bar for potential moves will be higher and more pruning can be done.