The Task Monitor (Taskmon.exe) creates the *.Lgc files in C:\Windows\Applog. The Taskmon.exe cannot be seen when doing CTRL+ALT+DEL, but it can disabled using Msconfig, where it is listed in the Startup-Tab (If not it is already disabled). If having a low end computer then one should consider disabling the Task Monitor as it uses resources for monitoring applications and leads to even lower performance.
The Defrag creates the file C:\Windows\Applog\Optlog.txt, which contains the information of what optimizations have been done. One can disable defrag from using the Applog entries by starting Defrag and click the Settings-Button and untick "Rearrange program files so my programs starts faster" (Not recommended).
The defrag can be configured even more:
Note some recommend that only activating the TaskMonitor when a new application is installed, where one starts and stops the new application a few times, then disable the Task Monitor again. This will generate a lgc file for the new application so defrag will keep it optimized.
[HKEY_LOCAL_MACHINE \Software \Microsoft \Windows \CurrentVersion \Applets \Defrag \AppStartParams]
UseProfile = 1 (Enables the use of the *.Lgc files in Applog)
MinLogSize = 1000 (Ignores all *.Lgc files below 1000 bytes)
MaxNoUseDays = 90 (Ignores all *.Lgc files older than 90 days, 0 = Ignore age)
MaxApps = 50 (Only optimizes the 50 most used applications)
ExcludeFiles = "System.dat\User.dat\System.ini\Win.ini" (What files NOT to optimize)
More Info MS Technet
More Info MS KB186020
More Info MS KB186171
More Info MS KB197791
Related Defrag partitions to speed up file access
Related Faster defrag in Windows 98 using defrag from WinMe