If you have tried from unnecessary giant emails contacts journals, to-do-list, tasks, calendar and appointment etc knowledge, to resolve your large PST size issue. And in case you are still facing low performance of Outlook application then use SysTools Split PST Program to split giant PST file in to little size PST file which can basically manageable. Software has some advance key feature: - You can split large PST file easily and quickly. *Split all items of Outlook mailbox like emails, contacts, calendars, journal, tasks, etc. * Split large PST files into UNLIMITED smaller PST files. * Split all folders such as contacts, calendars, journals, emails folders (including Inbox, Outbox, Deleted Items, Sent Items, and Drafts etc). * Support entire MS Outlook Version like Outlook 2010/2007/2003/2002/2000/97. * Compatible with all Windows OS such as: Windows 98/ME/NT/XP/2000/2003/Vista/Windows 7. Get free demo version for split 50 PST files items. After using demo version if you need to Split Outlook Storage then you have to purchase full version which is available into short cost at only $49. For more info:- http://www.splitpst.org/split-outlook-storage.html