Hard Disk Monitoring

I have a 5 years old ssd sata m2 Toshiba, and it was slow to access, even without system working on it. eventually I tested it with HDS. I decided to do a write test on it (destructive) - yes, yes, not good, it wears out ssd, yes I know. My theory was that, if there would be bad cells/blocks on it, I wouldn't be able to write and after read in some of them, and the "bad" block would be visible. So I did it. After the write test, I decided to perform a second write test. Now it's incredible, speed is x3! How could a write test "regenerate" a ssd?
I also wondered if the "optimize" feature of windows 10 works well. Or not so well. I can TRim the ssd totally offline from time to time, I think I'll try this. also. My experience on classic hdds on the past 20 years showed me that MS tools are not bad, but sometimes not good enough, and some maintenance may be done offline with success and good results. CHKDSK even at reboot is not always perfect - but it's another story now.
Just my question about the write test on the ssd, regenerating it - what happened to this ssd? I don't get it. Thank you.

The answer is very simple: generally the write "refreshed" the SSD. It is completely normal and expected situation: "old" data stored could be harder to read back (so generally the SSD is constantly become slower and slower).

Many SSDs automatically "refresh" the stored data - but (exactly because this can degrade the health) it may not happen at all or just happen very rarely.

But if you perform any kind of write testing under Hard Disk Sentinel Disk menu -> Surface test when the drive is a secondary (non-system drive) like

- write test
- write+read test
- reinitialise disk surface
- read+write+read test (refresh data area) - this designed exactly to "refresh" an old device by rewriting the data

then yes, the SSD will be much faster, ideally it will re-gain the lost performance.

TRIM is irrelevant in this area. TRIM will free up the UNUSED space but it has no effect on stored data. Chkdsk etc... will also make no difference.

Tip: for many SSDs, the Disk menu -> Extended self test function can be also used to "refresh" the data. This performs the internal hardware self test function of the SSD which can safely re-fresh the information even on a system drive, without the need to overwrite / clear the drive.
According the experiences, the Disk menu -> Extended self test function in Hard Disk Sentinel could help to re-gain lost performance too.