SSD Performing Poorly

I have a MBP 17 2010, equipped with a Vertex 2 SSD 120GB as boot disk.

It's an old hardware but I don't want to change it, the problem is the SSD is performing poorly :

The SSD health report is not so bad (except for temperature, which I dont understand) :

the SATA link looks OK :

EFI version is the latest :

but the speed, especially write speed, is quite the half of the Vertex 2 public benchmarks.

Any help ?