Generating pdf drawings Rhino 5 & 6 differences

Hello,
i am using custom display modes in Rhino to generate technical drawings to .pdf files. Below You can find two example of using the same display mode, but generated from Rhino 5 and Rhino 6. Can someone explain, why it is looking normal in rhino 5 and in rhino 6 there are those thick lines and it is not possible to use it.
With simple drawing it is not a problem to make it in Rhino5 and generate .pdf from it, but when there is a bigger model with some .stp files imported in it (more details), rhino 5 starts to struggle and drawing loading process is taking ages.
Looking forward for You advices!
RHINO 5:

RHINO 6:

You have a lot of additional variables you haven’t accounted for.
First, are you using the same PDF Authoring tool in V5 and V6?
V5 didn’t have one, V6 included RhinoPDF.

Second, the display pipelines in V6 are totally different than V5.
This is also affected by your antialiasing settings in Rhino.

This is why the display mode settings can be adjusted and changed.
I have gone in a tweaked these settings for V5 and V6 in both Windows and Mac. My tweaks are different on my different computers. I adjust them until I like how they look on my screens.