There is a far more insidious problem with modern drives and the windows NTFS file management system -
NTFS holds all the file entries, descriptors, ownership and allocation details in 1 big 'heap', and includes the data from small files.
Using FAT - the entries for files in a 'Folder' were held in a 'Directory file' that had the same name as the Folder, so getting all files in a folder meant finding the 'Directory file' and reading that.
In NTFS it means having the file management part of the OS search through the MFT looking for file entries that are marked as being in the 'Folder'(s) you specified.
No problem as long as the OS has enough (real) memory to allocate to hold all the MFT.
Then, one day, you will create a new entry and suddenly the real memory available is not enough to hold all the MFT
Now the OS will begin looking for the least-recently-used memory block so it can re-allocate that to the bit of the MFT that needs to be read in.
And then - the next bit of the MFT to be used was in the bit of memory that was previously least-recently-used - so find a bit of memory to re-allocate for that data to be read from the drive
(no - it won't be in the drive cache as that did the same thing as the OS did with it's cache.
Repeat for every block of the MFT down to the entry for each and every file you wanted - or that is in the folder you wanted to get a file from.
That can cause hundreds of milliseconds of disk access for every one of the - say 1000 files in the folder you want to open a file from.
So - more important than defrag may be to remove the redundant temporary Internet files - maybe 2000 for every day's browsing.
NOW - does anybody know of a utility to defrag and reorganise the MFT - please, pretty please!