Additional information / tries to narrow down the issue:

1) I tried it with another computer --> no major improvement.
[I tried to link a snapshot picture to mediafire and imgbb but both didn't work here]
2) I exchanged the floor texture with colors --> major improvement
[I tried to link a snapshot picture to mediafire and imgbb but both didn't work here]

3) I fully zoomed out that I only have one axis to scroll (in this case up/down) --> improvement with texture in only one scroll dimension.

4) Scaling of the texture from 300% back to 100% --> no impact.
5) Changing to another (simpler) looking texture --> no impact.
6) Hiding the floor --> major improvement

It seems that the texture processing / rendering in the 2d view is the problem. Especially in two dimension scroll what you usually do with a mouse (e.g. diagonal).

Interestingly the 3d view is perfectly smooth with all textures in it.
How does the 2d texture processing / rendering works? Is it maybe without hardware support? Is it possible to change it / improve it?