Hi Rickard,
Can I ask one thing? (Didn’t see it in the thread) Is this with 32-bit or 64-bit version of N5.5/N6 ?
If it is 32-bit it can be explained by RAM usage. Because N6 32-bit uses more RAM than N5.5, and thus can make problems if you are on a brink for resources.
Best,
Pål