BackupBuddy creates a single process to initiate transfers. Using a single process can be a problem with larger websites because the larger your website, the more likely it is to reach server limits, e.g., PHP max execution time; Apache timeout, etc.
It is best to keep your backups within a 150MB limit to a remote FTP server to avoid reaching timeouts. It is also good practice to download your backups locally. That way if your backup fails, you will be able to upload your data to the new site.
If your website is hosted with We Push Buttons then Backup Buddy should run without a problem. If your website is hosted elsewhere some web hosting companies don’t allow Backup Buddy.