To free memory, you can use programs to defragment and free up memory (RamBoost, etc.).
These programs are supposed to free memory in Windows. In reality, they are not only unnecessary, but often slow down the functioning Windows instead of speeding it up. They use a huge amount of memory (they are calling a lot of RAM for Windows). In response, Windows tries to free memory by copying blocks of memory programs background on disk (in pagefile.sys). This operation is called swap out. Thereafter, these defragmentation programs release memory that they have just allocated. So in theory, this frees much of the RAM.
But in practice this operation caused disk write. When you click again on one of the programs in the background, then Windows must return all data in memory (swap in), which again causes disk accesses very important. So these programs cause intensive disk access, forcing Windows to swap blocks of memory for nothing (instead of letting Windows do it when absolutely necessary). The hard disk is thousands of times slower than memory, this causes a global slowdown. The programs that require real-time operation (such as CD recording software) may be disrupted by the swapping of Windows.
Defragmentation of memory is a myth. The programs never have access to actual physical memory addresses and always work with virtual addresses.
Only the operating system knows which are physically placed blocks.