SSD not so fast as the first time ...

[AGANG]

HI!

When I bought my 2015 13" Retina Macbook Pro with 512GB SSD (with Yosemite), I ran a Black Magic Speed test and It showed me about 1300 MB/s write and read speed. Nowadays I ran a Black Magic again after 4 months later (with ElCapitan) and It showed me only 600 MB/s write speed (half as the first time!!!) and 1200 MB/s read speed.
At the first time I had 500 GB free space now I had only 20 GB.

My Question is: How can I get again 1300 MB/s write speed?

Under you can see the pictures of Black Magic results.

Thank you

 

[CoastalOR]

I think a big part of the problem is how full your SSD is. You have less than 4% free space on the SSD. I've read people recommend 15% to 20% free (unfortunately I do not have specific official reference links). You could do a search recommended SSD free space.

 

[navaira]

I was looking around for a similar thread and found this – just tested my rMBP and found that, indeed, same as original poster's problem, write speed dropped to 617 MB/s. Read is at 1414 MB/s. Filevault is disabled and system reinstalled 2 days ago (I tried Sierra, discovered Karabiner doesn't work, restored from Time Machine). It's a 128 GB model with 33 GB free. I scanned it with Disk Utility which fixed something in headers – before the scan it was even slower at 480/1100 MB.

Any hints?

 

[robvas]

Was the 128GB model ever faster than that for write speeds?

 

[navaira]

Yup, at the beginning I had similar speeds as the OP. I don't have a screenshot but I was all excited about the speeds as I've never seen anything like that before.

 

[leman]

SSDs are known to slow down as they fill up. But in any case, its very unlikely that the reduced speed will have any impact on your normal laptop use.

 

[navaira]

Yes, of course. I was just surprised to see the speed drop to 50% – I've wondered if perhaps it would help if I did a clean reinstall of El Capitan, then restored from TM rather than just straight restore?

Did some cleanup in the meantime, now waiting for Spotlight to reindex.