My 1TB samsung laptop hdd has recently become very very slow.

I request Splidit and Fzabkar to enlighten how to make it normal?

Other members are also requested to give suggestion.

Have backups? If yes, you can try Harddisk Sentinal or anything similar - Read test only at first. Some read/write tests can be data-destructive.

_________________
"Take care of thy backups and thy restores shall take care of thee." Ben Franklin revisited

I know this might sound a little mysterious to some but I remember that I've seen cases where WD and Samsung HDD's (both 2.5" as well as 3.5") showed really slow seek rates (within the underlying file-system) but SMART and surface seemed to be in very good condition (no Errors, low realloc-count, ...).

After wiping the entire disk (either with zeros, 0xFF or any other pattern) in order to prepare it for disposal I've further observed those disks were coming back to life meaning seek rates went back to a far more sane levels. I remember that I first blamed FS-internals like MFT-bloat for this but came to wonder when a non-NTFS-disk showed a similar behaviour...
Then instead of dumping those disks I continued to use them for occasional data storage and they stayed in good condition for a longer period (=were not pre-fail).