I have the same MacBook. How does the extra 4 gigs of RAM affect performance?
Edit: Well, I guess that since you upgraded your storage at the same time, it might be difficult to tell what any performance improvements were due to.
I had this very machine (once upon a time) and I did a number of upgrades and reported on them in the Mac Pro Photoshop benchmark thread:
https://forums.macrumors.com/showthread.php?p=8953494#post8953494
But here some more details (upgrades done in this order and starting from a factory setup):
Jump from default 5400 rpm to double-sized 7200 rpm:
Pros:
+ more space

+ Application (PS, others) specific performance increase: none to moderate
Cons:
- more noise and noticeable vibration
- more heat
Jump from 2 GB to 4 GB RAM
Pros:
+ slightly snappier
+ better multitasking performance
+ Application (PS, Aperture) specific performance increase:
immense
Cons:
- none
Jump from 500 GB 7200rpm HDD to Intel X25-M G2 SSD (80 GB)
Pros:
+ Whoa! It felt so snappy it was hard to believe it was still the same machine.
+ Application (PS, Aperture) specific performance increase: faster application loading. Otherwise no performance increase.
+ Silence (blissful sigh), battery performance increased by 30-45 mins.
Cons:
- Where shall I put all my stuff?
Jump from 4 GB to 8 GB RAM
Pros:
+ multitasking performance better, but barely noticeable (may be more relevant without snappy SSD paging) and only under high strain. (YMMV)
Cons:
- none (price)
NOTE: All these results were with 10.5
So,
If you already have 4 GB of ram, you should have a look at activity monitor to ascertain whether 4 GB suffices or 8 GB would give a boost.
In my opinion, a SSD makes a world of difference in all usage types except when you are using the machine as a number-cruncher (running seti@home, handbrake or something like that). The general responsiveness improves like you won't believe.
RGDS,