Should I get more RAM or install an SSD?

It's very easy to determine if your Mac's performance is being limited by available memory. Please read Use Activity Monitor on your Mac - Apple Support. If the "Memory Pressure" graph is frequently "red" your Mac will benefit from additional memory. If not, it won't.

To install additional memory refer to Memory Upgrade Instructions in the  (Apple) menu > About This Mac > Memory.

Both will make it faster.

A SSD will help with reading & writing data, the OS spends a lot of time doing this - it can be what the wait cursor signifies (the spinning beachball).

RAM is used as short term storage, Applications that do a lot of calculating use lots of RAM but web browsers also tend to eat it up too. You can quit apps to reduce your RAM usage. When you run out of RAM the OS is forced to write it to the disk - which is much slower.

Post an etrecheck report if you want better advice on your system. Slowness can occur if you keep installing more applications & do not consider correctly removing ones that are no longer used. Migrating from older systems can also bring over performance issues.

https://etrecheck.com/

If I had to choose just one, I'd probably get an SSD first provided you can get one large enough to store all your data & have room to grow.

Hi,

It depends on how much RAM you have now and what your uses are. If you have 8GBs and "normal" usage, 8 should be fine and I'd get the SSD. If only 4GBs, I'd get the RAM depending on what the etrecheck shows about Swap used (when RAM fills up and uses much slower HD). You can also check this, and Memory Pressure (after you've run for awhile doing normal activities) in Activity Monitor, which is already installed on your Mac in the Utilities folder.

Over the life of the computer, a total of read-writes to a hard drive

or an SSD could be depreciating the durability of either drive type.

While RAM chips hold active data for short duration, it isn't read-

written from the SSD or HDD; & that is where applications look for

quick accessible short-term memory. If the computer had, say, a

750GB 7200-RPM rotational HDD, then I'd say upgrade RAM fully.

Usually a slower 5400-RPM HDD of 1TB would drag the Mac down

and even if your computer could run a higher 16GB total, the slow

point would still be this read-write of temporary swap or virtual ram

to the storage drive. While an SSD is faster, the wear factor may be

insignificant if SS drive has adequate reserve over-sampling capacity.

While I've a Mac with dual 1-TB 5400-RPM HDDs factory installed,

I chose 16GB RAM upgrade as that was easier & cheaper than SSD.

And I've been eyeing owc mercury pro SSDs; to replace both HDDs.

Good luck in your choices, in any event...! 🙂

Do both. I did. Mac OS sierra will eat up 10-12gb of ram immediately.

SSD upgrade should be priority for best performance however ram is cheap so do both While you have the MBP open.

Also consider a NEW battery.

RAM

I used "Crucial brand ram" works great no problems

SSD

I used "crucial" brand SSD "MX200" or MX300

Battery

Look for an "Anker" brand battery for your MBP.

Don't buy a cheap knock off. They dont work and could cause your MBP to run hot.

You can find all these parts on Amazon.com for cheap.

cost me about $200 for a 500gb SSD and 16gb of ram.

Also, try resetting the SMC: https://support.apple.com/en-us/HT201295