If by too many items on the x-axis you mean too many data points, then one possibility is to reduce the resolution of the data your chart is based on (i.e. if it's a timechart, reduce the span).
But did you know you can zoom in on a line chart? Click and drag between the points on the x-axis you would like to zoom in on. That way, you can keep the high resolution of your data and be able to view selected areas in more detail while still offering the full picture when not zoomed in.
Another possibility could be to split your chart into two (or more if necessary) separate panels and using half (or less) of the original timespan for each of the panels. This will kind of emulate a pagination, but it requires some thought on your side as to how you want to split and apply the timespan, so it's not as comfortable as what you might have had in mind. It will also use more space on a dashboard.
I'm curious though why you would need this, because usually the width of a screen is more than enough to display relevant data. If it doesn't fit, then your visualization is probably not entirely appropriate - e.g. you should be using a smaller timespan, or filter more strictly to reduce the amount of data contained in the visualization.
Conclusively, a real pagination doesn't exist in splunk as far as I know, but maybe the above ideas can help you deal with that other ways. If this doesn't satisfy your question, feel free to ask further!
