Meant to say the problem is the jerkyness of the scrolling.
First, if your monitor isn't refreshing at either the same frequency as your sequence or double it, that can cause this. Which is why it's good to have a monitor that comes with refresh rate settings to match video work.
Second, IF the monitor is showing them correctly without visual jerkiness, you need to have whole-number vertical movement per frame.
Set your timeline timecode to Frames. Then count the length of time in frames that you want to have for your crawl.
Now you need to do a bit of math. Your vertical motion needs to be a multiple of the 'horizontal' motion ... the frame count. In even "whole" numbers.
So you have a vertical scroll ready ... and it's say 9,000 pixels total 'height'. You want a typical 3 pixels per frame movement ... so you need to set the length of that scroll on the timeline to 3,000 frames.
But if you want a slightly slower 2 pixels per frame vertical movement, then ... you need to adjust the 'length' or frame-count of the crawl to 4,500 pixels. Because you need an exact number of pixels in whole numbers.
If you can't divide your pixel height of your crawl by the speed in frames of movement, then you need to make small adjustments to your crawl to get that so that you have a whole number pixel count.
Neil