A lot of programs are started by default in each desktop session. Many of them are unnecessary; some of them are annoying or can cause problems. users can disable everything they don't need.

To change which programs are active, run the session properties control panel tool for your desktop:

• Gnome: gnome-tweak-tool (not in the application or actions menu any more, nor part of the settings panel, so it has to be run from the commandline!).
• Cinnamon: cinnamon-session-properties, it is in the “System settings control panel” app.
• Mate: mate-session-properties

On the tab “Startup programs”, remove the checkmark in front of the command you don't want.

The following services are useless on our desktop systems and can safely be disabled (some already are, in our default install, but it doesn't hurt to make sure!):

• Blueman (Bluetooth, not present on most systems)
• esc (smartcard security utility, not present)
• PackageKit (update notification; not usefull to users since we install the updates for you)

Also: use gpk-prefs (or the preferences from the notification icon to disable these notifications)

• Network (NetworkManager control tool; very usefull for wireless connections, but useless for desktops with a fixed network connection)

These services may be disabled if you don't want them, but that is up to you; they can be useful, if configured properly:

• mail-notification (A mail icon in the panel, needs to be configured and it pops up a configuration dialog on every login if you have not configured it yet, so if you don't use it, get rid of it)
• User sharing (a tool that allows users to share a directory with other users)
• User folders update (updater for the “special” directories like Documents, Downloads etc)
• ABRT - automatic bug reporting tool. if a program crashes, this program will attempt to file a bug report. But you will need to register in the fedora bug tracker, and it will be useless for programs from other sources (e.g. IDL or own programs)
• Caribou: on-screen keyboard (nice for tablets, useless in most other cases)
• Disk Notifications - gives a popup if a disk is almost full. No quota warnings, however.
• Evolution alarm notify - useful to get alarms from the calendar in Evolution, but useless if you don't use Evolution or its calendar.
• Tracker - the Gnome 3 search tool. There are 3 services running and since tracker tries to index all files, including those on network disks, it will be slow, and its cache and index (in home) will be large.
• Zeitgeist-datahub - Another search/history tool in GNOME and Cinnamon. Can be useful, if used (similar to the search features in Google Now and Apple's Spotlight, including searching recent files, recent apps, web history etc). But if you don't use it, it is a waste of memory.
• Depending on your desktop choices, there may be duplicates in the session, eg: screensavers for Gnome, and for Mate. Disable whatever you don't use to speed things up a bit.