Could you not easily upgrade the RAM to 16gb on the W500? Disk upgrade to 512GB should also be doable. (My x220 has 16Gb/512Gb and it does well for similar vm based setup.) Or do you have an older model w500?
My x220 limited to 8GB in ever bit of published Lenovo literature, but I bought 16GB of RAM at the same spec as the 8GB I have running now and everything works fine.