IMO -- here are things I've found make Tableau enjoyable on a laptop (currently on a Lenovo W541):
1. give me RAM!! -- I like 16GB minimum.
2. give me a solid state hard drive -- they are soooo....fast that when swapping out of memory to RAM is needed by Tableau, I don't typically see much of a delay.
PS - the last element that I prefer is for there to be an on-site PC that I can remote into. On-site PC's typically have much better network connectivity than connecting through VPN to the data servers. As such, while I may do some data wrangling from my VPN laptop, that is mostly on smaller models. Any seriously large dataset that needs to be extracted is done via remoting into an on-site PC so that the network lag is made as negligible as is permitted by the company.