Compacting is a common and heavily used operation in different application areas like statistics, database systems, simulations and artificial intelligence. The task of this operation is to produce a smaller output array by writing selected elements of an input array contiguously back to a new output array. The selected elements are usually defined by means of a bit mask. With the always increasing amount of data elements to be processed in the different application areas, better performance becomes a key factor for this operation. Thus, exploiting the parallel capabilities of GPUs to speed up the compacting operation is of great interest. In this paper, we present different optimization approaches for GPUs and evaluate our optimizations (i) on a variety of GPU platforms, (ii) for different sizes of the input array, (iii) for bit distributions of the corresponding bit mask, and (iv) for data types. As we are going to show, we achieve significant speedups compared to the state-of-the-art implementation.