Summary. Apple Dashboard Widgets sometimes get installed along with other software.
For example, if you install software for an HP printer, there is a Widget that gets installed (unless you choose not to).
Each widget uses up extra virtual memory and requires some attention from the CPU — slowing down the computer.
Check Memory Usage. To check and see how much memory is being used by Apple Dashboard Widgets on your computer, open the Activity Monitor (found in Utilities), and view the System Memory page. Sort all items listed by Virtual Memory to view those taking up the most memory at the top of the list. You’ll likely see DashboardClient toward the top. Or, you can sort alphabetically and look for DashboardClient.
Remove Unnecessary Widgets. To remove the Widgets running in the background, press the F4 key on your Apple keyboard to reveal all enabled Widgets, then press the plus + in the lower left of the screen to edit the Widgets. Click the small x in the upper left of each Widget to remove it.
“I discovered about 800MB being used by my Dashboard Widgets. There were actually two instances of the DashboardClient running. After following the above steps, the DashboardClient was gone and my 800MB of memory were back!” ~ Greg Johnson