It’s about courtesy and consideration, not time lost.
I do get mildly annoyed when people trundle around at 40mph because it’s annoying, but they are mostly old todgers who don’t feel confident going any faster. So if it’s either that or house arrest for them then so be it.
I don’t get annoyed with tractors or lorries – they have no choice. Caravans also – they want a decent UK holiday then fair enough. I DO get annoyed with caravans taht don’t pull over at let folk by though when there are lots of chances.
What I don’t like is people indulging their fetish for speed on the open road at the expense of everyone else. I do sometimes feel like a nice drive and go a bit fast (although very rarely over the limit unless motorways), but when I get stuck behind something slow I just accept it, cos it’s a public road and we all need to play nicely. I pass when there’s a good opportunity. I don’t cut it fine and I don’t take risks whilst passing.