WPTC uses incremental backup technology that's different from existing solutions. It doesn't compress your files and upload it to your cloud (Google Drive, Dropbox, Amazon S3) like traditional backups. The files are directly uploaded as they are on your site. Hence it takes a while for the first backup to complete depending on the number of files and the size of your website. It doesn't overload your server while doing that either. Only the first backup takes long, the next set of backups would be much faster. Check out the video below on the advantage of Incremental backups.