Why does backup take SOOOOO LONG…???

The latest backup took 26 HOURS to complete, because it appears to just STOP at regular intervals for hours at a time. This last backup started at 22:29 on Wednesday and didn’t finish until 01:09 on FRIDAY.

Can someone please answer this and tell me why this is taking so long…???
Here is a summary of the backup:

========== Start: 31 May 2017 22:29pm ==========

22:29:14: Backup started on Wednesday May 31, 2017. 
22:29:14: Your time limit is 300 seconds and your memory limit is -1 
...
03:57:29: Starting SQL backup. 
...
04:02:11: Processed 2099 files. Approximately 40% complete. View uploaded ? 
06:07:48: There has been no backup activity for a long time. Attempting to resume the backup. 
07:32:21: Processed 2099 files. Approximately 40% complete. 
...
07:37:00: Processed 2303 files. View uploaded ? 
12:16:52: There has been no backup activity for a long time. Attempting to resume the backup. 
14:25:06: Processed 2303 files. Approximately 43% complete. 
...
14:29:44: Processed 2513 files. View uploaded ? 
16:00:53: There has been no backup activity for a long time. Attempting to resume the backup. 
17:57:15: Processed 2513 files. Approximately 47% complete. 
...
18:01:57: Processed 4398 files. View uploaded ? 
21:52:09: There has been no backup activity for a long time. Attempting to resume the backup. 
01:05:50: Processed 4398 files. Approximately 83% complete. 
...
01:09:03: Processed 5811 files. 
01:09:07: Backup complete. 
01:09:07: A total of 5900 files were processed. 
01:09:07: A total of 82MB of memory was used to complete this backup. 

========== End: 2 June 2017 01:09am ==========

TOTAL BACKUP TIME: 26hrs 40mins