The Memory Defragmenter allows you to perform a defragmentation of Windows used memory.
On Memory Defragmenter's main window (under Parameters tab), you'll see an Initial Status, shown Total and Available Physical Memory (available at the very moment you launched Memory Defragmenter).
How much memory to defragment?
Next to Initial Status, you'll found a slider, which allows you to specify how much memory to defragment. The recommended setting is the third part of Total Physical Memory. If you're positioned on the slider, you can set the default with the D key (for Default) on your keyboard.
Shows the actual amount of available physical memory, in KB and with a graphical (as progress bar) and percent representation.
You can define an automatic defragmentation process specifying how many minutes to defragment. This option can be enabled and disabled checking the Defragment Every's box.
This is a graphical representation of the entire defragmentation process for your current Windows session. The red line symbolize the initial status (before defragmentation) based on the value of Available Physical Memory when the defragmentation process started. The green line symbolize the free memory after a defragmentation ended. The defragmentation process reclaims free physical memory when possible, this doesn't mean that every time you do a defragmentation process you'll get more free memory than when started.
This section will show you a log of each defragmentation process. An icon with a person at beginning of a line, means that process was requested by user. Automatic defragmentation appears with a memory icon. You'll get the time when defragmentation was processed, Start Memory (available memory before defragment), End Memory (available memory after defragmentation), and how many KB was freed (positive value) or how many KB of memory was really needed by Windows after defragmentation (negatives values means that).