Lack of speed affects writing only, or reading too? Writing depends on many circumstances, for example copying a fair amount of small files can slowering the drive significantly. Or if reading is also affected - as I wrote to another post: typical Seagate HDD disease is a slowdown (named "slow responding issue" - usually it has one or more weak heads and the resulting unstable / bad sectors that are diligently collected by the firmware and this slows down the drive - i.e. overrides the firmware to stop write / read operations because sector list data cannot be updated) the first sign is the dying of the drive: weak heads constantly developing bad sectors - if one or more of them in the disk's Service Area - named SA, where the neccessary informations stored to up & running the drive itself). When they start to slow down noticeably it means their end, because under the hood, only the "chewing gum" holds them together: they are full of bad sectors, but the firmware can still replace them from the spare area for a while. In this case (using home methods), your drive can't stand a full user data area backup. If the drive has not stopped completely, special software developed for data recovery can be used to disable the weak heads and turn off realtime error-correcting background processes, thus speeding up the drive, then the other heads can make a Bit-perfect disk image copy of the sectors covered by them at normal speed, and then by switching the faulty heads back on, one can also try to save it's sectors. Thus, by putting as little stress on the drive as possible, there may be a minimal chance of recovering the data without breaking it and replacing the head block (because that would make it significantly more expensive - unfortunately, the heads have often been degraded to such an extent that the replacement cannot be swept away). If the drive loses more reading speed and the content data is important, take it to the nearest data recovery company in your area immediately (or make a backup on your own, if you can).