Is it better to have 4x2GB or 2x4GB of RAM?
I recently upgraded my iMac (2010) to a 2x4GB RAM configuration and that went well, but I've considering putting the old 2x2GB in as well to get to 12GB. I didn't initially as I've read more modules is usually slower, but the comparison is usually between equal total amounts of RAM (see Is it better to have 4x2GB or 2x4GB of RAM?).
What would the performance gains losses look like when comparing 2x4GB and 2x4GB plus 2x2GB in a 2010 iMac? Would the extra 4GB be worth any speed hit?
My usage is generally heavy dev, potentially 2 VMs running inside OS X with Eclipse, XCode, and TextMate open. And TONS of browser tabs (I often reach over 2GB in browser RAM).
(All RAM is same clock speed and timing.)