In adding my own custom logic hooks for relationships, I determined that Sugarbean is unnecessarily deleting and re-adding relationships during Save() even when no relationship changes were made. This is because there is no test that checks for the change before the Link delete/add functions are called.

I posted this as Bug #31775 and labeled this a defect because of the unnecessary overhead this puts on so many aspects of the system.

Here is the diff output from a change I made to SugarBean.php (5.2.0f) to correct this issue:

Code:
1858,1864c1858
< $rel_changed = 1;
< // EJG Update to check for relationship change
< if($this->rel_fields_before_value[$def['id_name']] == $this->$def['id_name']) {
< $rel_changed = 0;
< }
< // EJG End
< if ($rel_changed && !empty($this->rel_fields_before_value[$def [ 'id_name' ]]))
---
> if (!empty($this->rel_fields_before_value[$def [ 'id_name' ]]))
1866d1859
<
1873c1866
< if ($rel_changed && !empty($this->$def['id_name']) && is_string($this->$def['id_name']))
---
> if (!empty($this->$def['id_name']) && is_string($this->$def['id_name']))