Selection Tool is painfully slow using trackpad in InDesign

I'm running the latest 2017 version of InDesign on Mac Sierra OS (though I think the problem cropped up on 2016 version too) on a MacBook Pro.

In short, my trackpad/selection tool/text tool drags really slowly when on the pasteboard, to the point where it is actively slowing down my workflow and causing jobs to take far longer than they should.

I don't think it's a trackpad problem as it works fine in every other application, in Finder, in browsers etc.

In InDesign it returns to its normal speed when I am off the pasteboard (for instance, accessing panels or the toolbar, it reverts to how it should be) but on the pasteboard/working on a document, it's dreadful! I've trashed preferences, restarted etc.