CPU: This will do the most work out of all the other components, generally speaking. That's what counts the most as you already know.
GPU: Needs to be strong enough for 1x IR. Basically anything that's not bottom-tier integrated graphics (think Intel HD 4000) will do for most games. If you go beyond 1x IR or add things like AA, then you need a stronger GPU, but you can always cut back the enhancements to regain performance. If your CPU is too slow though, upgrading your GPU or getting a better one will do nothing, however.
RAM: Irrelevant for performance. Most systems come with 2GB minimum (4GB seems standard though) and that's enough. RAM doesn't affect performance, but obviously don't try to run Dolphin on something like 128MB...
Free Memory Space: Irrelevant for performance.
DDR3/DDR4/SSD: Irrelevant for performance.
GPU: Needs to be strong enough for 1x IR. Basically anything that's not bottom-tier integrated graphics (think Intel HD 4000) will do for most games. If you go beyond 1x IR or add things like AA, then you need a stronger GPU, but you can always cut back the enhancements to regain performance. If your CPU is too slow though, upgrading your GPU or getting a better one will do nothing, however.
RAM: Irrelevant for performance. Most systems come with 2GB minimum (4GB seems standard though) and that's enough. RAM doesn't affect performance, but obviously don't try to run Dolphin on something like 128MB...
Free Memory Space: Irrelevant for performance.
DDR3/DDR4/SSD: Irrelevant for performance.