This question serves to share and collect the enhancements that make a large difference to how you use your Mac.
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The best answers will not only list a feature, but provide details on how to configure that feature, and provide an image of how to use the feature to be more efficient or effective with Mavericks.
Best Answer
The overhaul of the virtual memory system makes it clear that memory pressure is the primary factor to track and not how many free pages, inactive pages or overall virtual memory is allocated.
The bottom panel is invaluable for diagnosing a slow machine and knowing whether to rule out memory contention as a cause of the slowness. After running your Mac for a week, you should reach a nice steady state like shown above and can know if adding more RAM or adjusting the programs you run will affect performance.