Very bad performance with nvidia driver on M3800

I am running 14.04.2 LTS with nvidia driver 346.59. Have also tried with 331.113 (but understand K1100m suport came in 340), 340.76 and 349.12 from xorg edgers.

I have kernel 3.16, have also tried 3.13 and the newly released 4.0.

I have not a system with preinstalled linux as it was not available in my country. It is the same hardware though (the 2015 version with thunderbolt)

Using the nvidia driver I get around 220 in glmark2 and with the intel card I get around 2400. Something is clearly wrong. Scrolling in webpages is slow and laggy.

Does the factory installed machines have some extra packages or config that solve this? I thought it was a plain 14.04 LTS install?