I was in the supermarket just now and the till was responding very slowly (i.e. there was a long wait for the prices to come up after the item was scanned).
I remarked, "천천하지", but that felt wrong to me - but a native Korean confirmed that 느리지 was more appropriate. But why is this? Is it because 느리다 is more appropriate for talking about a long wait, rather than literal motion? Or is it more appropriate for an exclamatory observation than 천천하다?
In general, what are the differences in usage and meaning between 천천하다 and 느리다?