This is either due to an inconsistent Wi-Fi signal strength, or the download is pausing to make updates or changes for further installation of the download. Most downloads come with an anticipated download time based on the slowest speed necessary for downloading the installation or software. As long as the install is within those provided time frames, there should be nothing to be concerned about. Increasing your internet signal and strength will make for more rapid downloads. This can easily be accomplished by moving your tablet closer to the Wi-Fi router.