Why doesn't my program's memory usage return to normal after I free memory?

Question

consider the next sample application

program TestMemory;


{$APPTYPE CONSOLE}

uses
  PsAPI,
  Windows,
  SysUtils;

function GetUsedMemoryFastMem: cardinal;         


        

Answer 1

Any memory manager (including FastMM) incurs some overhead, otherwise Delphi could have just used the Windows memory management.

The difference you observe is the overhead:

• structures that FastMM uses to keep track of memory usage,
• pieces of memory that FastMM did not yet return to the Windows memory management to optimize similar memory allocations in the future.