How much will SSD Improve Performance?

[StellarVixen]

My experience from adding a SSD to a late 2011 MBP:
Measurements using Blackmagic Disk Speed Test
OEM 5400 RPM HDD: Write 68 MB/s, Read 67 MB/s
New SSD: Write 230 MB/s, Read 253 MB/s

Another problem that could effect performance would be a degraded internal disk SATA cable. If you install a new SSD and you do not see the speed improvements then take a look at replacing the SATA cable.

That is because of SATA II bus, SATA III is even faster.


Mid-2012 is gonna have speeds around 500 read and 450 write for 512GB drive.

Yes, OP, you are gonna experience drastic improvement in speed and responsiveness. It has to be seen to be believed.

Boot up time, application loading times, Logic/GarageBand library loading times, Spotlight search duration...all of that is gonna see significant decrease in duration.

 

[Chiromac81]

Since you have usb 3 you can get better performance booting off an external SSD than the slow internal drive.

What do you do then with the internal drive if booting from an external and how do you tell the Mac that the boot isn’t coming from internal anymore?

And did you say a 2012 has thunderbolt or USB 3 so that’s the speed I need for a good external SSD to boot off?

 

[Chiromac81]

What do you do then with the internal drive if booting from an external and how do you tell the Mac that the boot isn’t coming from internal anymore?

And did you say a 2012 has thunderbolt or USB 3 so that’s the speed I need for a good external SSD to boot off?

Anyone?

 

[Toutou]

What do you do then with the internal drive if booting from an external

You are free to
a) ignore it
b) wipe it completely and use it for storage
c) leave the old OS intact (as a backup and to keep something bootable on the Mac) and use your old home folder for storage

how do you tell the Mac that the boot isn’t coming from internal anymore?

once — by holding the Option key at boot and clicking the external drive icon
always — by choosing the external drive in Preferences->Startup disk

2012 has thunderbolt or USB 3 so that’s the speed I need for a good external SSD to boot off

Yes, both Thunderbolt 1 and USB 3 are fast enough to reap the benefits of an SSD. Modern SSDs' write-read speeds are much faster than what both Thunderbolt and USB 3 can handle, so don't stress yourself over getting a top-of-the-line drive. Even a cheap one will do (speed-wise). And the huge difference you'll see won't even be caused by the I/O speed, but rather by the much lower latency that is inherent to SSDs.

I can't stress this enough — this approach is absolutely doable and the difference is huge. I'm not exaggerating a bit. It's night and day. Go get an external SSD, or a normal SSD + a USB enclosure, install macOS on it and boot off it. You'll be pleased.

 

[MattPer82]

This part is incorrect. The mid 2012 non-Retina MacBook Pro uses Intel's Ivy Bridge platform that uses SATA 3 (and USB 3.0). Due to overhead maximum SATA 2 speed is around 270 MB/s.

I'm typing this post on such a model with an aftermarket Crucial M550 1 TB SSD (less than 10 % free space so performance is a little degraded) that peaks at around 500 MB/s:

@Benjer

I'd recommend a Samsung EVO 860 (not QVO) with at least 500 GB since current Samsung SSDs rank among the most reliable and fastest ones on the entire market (mostly limited by their interfaces like SATA 3 or PCIe for NVMe SSDs).

I'using the same model of mbp 2012 and a kingstone 480gb ssd, but i have so poor performance 250w 310r that i'm thinking about changing the sata cable. Or maybe it's another kind of problem?
the strange thing is that the same kingstone second ssd on optical drive has better performance 450w 500r !!!