Maintaining CRM 2011 Job Schedules

The CRM 2011 background job schedule can be changed with this tool from CodePlex.

http://crmjobeditor.codeplex.com/

The MSDN blog gives a good overview

http://blogs.msdn.com/b/crminthefield/archive/2012/04/26/avoid-performance-issues-by-re-scheduling-crm-2011-maintenance-jobs.aspx