Merging incremental as full

[admin]

Why is merging full backups and all incremental backups slower than creating a new full backup and merging the old and new full backups into one?

If the backups to be merged are all full backups, the program simply deletes the previous full backups and keeps only the last full backup, so it is fast. When merging full backups with other backups, the program reads all data from the image files to be merged and writes it to the new backup image file, so it takes longer.