Enable PPT only for projects that require PPT enabled. As this PPT is a resource consuming operation, this should be enabled only for projects that really require them.
To disable it, the checkbox should be unchecked in site adminstrator as below
Enable Automail only for projects that require automail feature. The mail interval also should be set accordingly
Data in the recycle bin on DB should be deleted if its not required. That affects the performance of the DB