As one of the most popular IDEs for developing Java applications, Eclipse can be adjusted with plenty of preferences. Here are my five favorite adjustments to tweak the Eclipse IDE. It works well with either the newest Eclipse Galileo or one of the older releases like Ganymede or Europa.

1. Improve performance by modifying startup arguments Per default Eclipse starts with a low size of memory. This results in numerous garbage collections which slows the IDE. You can easily adjust the heapsize memory by setting vm parameters on startup. Use the -Xms parameter to set the minimum and -Xmx to set the maximum heapsize. I prefer to use 1 GB for both so the VM doesn’t have to increase maximum heapsize during runtime. On Windows systems put a shortcut to the eclipse.exe and edit the target with your prefered VM-settings: path/eclipse/eclipse.exe -vmargs -Xms1000M -Xmx1000M See here for a full list of supported startup options. To track the currently used heap memory and manually trigger the garbage collector to free up memory, go to Preferences -> General and activate Show heap status.
2. Improve performance by deactivating unused plug-ins Each distribution of Eclipse contains plenty of plug-ins. It’s possible to deactivate several unused plug-ins without uninstalling them. So feel free to re-activate them later on demand. Go to Preferences -> General -> Startup and Shutdown to configure which plug-ins will be activated on startup.
3. Automatically Organize Imports on save Eclipse is capable of adding imports to your classes automatically which is surely one of the most used features. The command can easily be accessed by using the appropriate keyboard shortcut. I recommend to let Eclipse automatically organize imports on save. Go to Preferences -> Java -> Editor -> Save Actions and activate Organize Imports. Feel free to add additional save actions here.
4. Refresh workspace automatically Per default Eclipse does not refresh the workspace automatically when some files in the workspace are modified from outside the IDE. So if you copy some resources into your workspace (e.g. some icons to be included into your UI) you have to explicitly press F5 on the changed project to trigger a refresh. It’s possible to let Eclipse refresh the workspace automatically, go to Preferences -> General -> Workspace then check Refresh automatically. Some people claim that this feature might impact performance, but I’ve not seen any issues so far even on large workspaces. Let me know about your impressions.
5. Improve Package Explorer by using Java Type Indicator Per default the Package Explorer uses the same icon for each class file. It’s possible to display different icons against the concrete file type, e.g. concrete class, abstract class, interface or enum. This can be activated in Preferences -> General -> Appearance -> Label Decorations. Just activate the checkbox Java Type Indicator.

I’m sure there’re plenty more useful Eclipse adjustments. I would appreciate if you share your favorite tweaks with me. :)