The RAM footprints of most development tools on Linux are also less than on other operating systems, due to shared libraries and not just shipping every dependency bundled with binaries. A developer on OSX told me he was close to maxing out his 16gigs of RAM, blaming it on having to run 2 vagrant VMs simultaneously while working. While I wasn't able to establish a conclusive cause of his sizeable memory consumption (he was busy), I spun up 3 vagrant VMs of my own, simulated work, and opened/visited many more sites in Firefox to try to hog resources. I could hardly break 4 gigs of RAM used (out of 16), in Ubuntu 14.04. 8 gigs might not actually be so bad if you're doing development work using tools that aren't shipped as complete packages, but rather adhere to the unix philosophy.

I look at my RAM usage on ubuntu sometimes and I suspect that about 40-50% of the machine's total use is due to adblock running on firefox.

Give µBlock[1] a try, it seems to use quite a bit less memory. I've also found it to block more ads by default.

[1]: https://github.com/gorhill/uBlock

I suspect a lot of this comes from OS X apps all shipping with most of the library dependencies, so there's no way of deduplicating libraries that are loaded in the memory. In Linux, shared libraries are used, at least with software installed by package management. OS X should benefit from a kernel feature something like Linux KSM (kernel samepage merging[1]), that scans for duplicate memory pages and merges them to shallow copy-on-write clones.

1: https://en.wikipedia.org/wiki/Kernel_same-page_merging