The Disk Defragmenter in Windows 10/8/7 offers some additional options compared to that in Windows Vista. Its command-line version has some additional switches, which are rather useful.
Defrag Command line switches
To begin, open an elevated command prompt window.
Type Defrag /? and hit Enter. This will show you all the defragmentation options and command-line switches.
Here is the list of Defrag switches:
/A Perform analysis on the specified volumes.
/C Perform the operation on all volumes.
/D Perform traditional defrag (this is the default).
/E Perform the operation on all volumes except those specified.
/H Run the operation at normal priority (default is low).
/K Perform slab consolidation on the specified volumes.
/L Perform retrim on the specified volumes.
/M Run the operation on each volume in parallel in the background.
/O Perform the proper optimization for each media type.
/T Track an operation already in progress on the specified volume.
/U Print the progress of the operation on the screen.
/V Print verbose output containing the fragmentation statistics.
/X Perform free space consolidation on the specified volumes.
So, if you open cmd and type in “defrag /C /H /M” it will run defrag on all volumes, at a higher priority, in parallel.
You might also want to check out some of the best free defragmentation software for Windows.