What's the mean of "short cuts"?

From a lexical point of view you can look for shortcut in a dictionary (I usually write it without the space).

In the quoted context it means the designer should find alternate ways to implement the same logic function, in order to optimize time delays.

In general, you can have many combinatorial nets which are logically equivalent but maybe one of them is faster because the signal passes through a smaller number of logic gates.

Using a mathematical analogy, if you calculate either 12x34+12x56+12x78 or 12x(34+56+78) you'll get the same result, but the second one is faster.