smooth scrolling credits

Setup :

Blender VSE :

Track 1 : video 1920x1080 25 fps
Track 2 : text png image : text on transparent background 1920x1080 : 250 frames
Track 3 : transform effect on track 2 : y -100 percent to Y +100 percent IPO curve linear from 0 to 100 %
Track 4 : track 3 alpha over track 1
render to full HD 25 fps 90 % quality 8000bps

Problem : scrolling text stutters a little bit (steps of some 5 pixels) instead of being smooth such as fast moving objects in the video.
Same observations with titler functions in other editors (I tried Kino, Cinelerra and Kdenlive) or in other formats (I tried PAL dvd)

Any suggestions to improve this ?

I find some tips like or or
but before investigating these I wanted to check if this will not give the same result. (I am familiar with the VSE but not yet with the other parts of blender).


(I posted a thread on the same subject yesterday but obviously it did not get through)