It isnt easy to explain but you spend almost no time on the path!
To get to high spy. climb up about 80-100 ft on the rocky path, but just after the first rough section look out for a trod across the grass to your right that goes all the way to high spy top.
Then - go cross country on a level traverse ( small trods generally visible) to the col you see between the two high points on the horizon about half a mile away.
Then - stay generally left, on trods to the right of the path, eventually being forced on the path by the terrain, all the way till you see a visible big fork in the path. Take the right hand fork on a slight incline to the horizon
Then Look for emmillous stones!!!! - you see the path swing in a long right hand bend over about, but a visible trod ( marked by emmis stones) completely cuts off this corner, go all the way on a level traverse till you finallly see cat bells.
The next bit is hard to explain. But basically ignore the path - which you see swinging in a left hand arc , finally fropping steeply to the col before cat bells.
Dead reckon the coll across grass heather, lumps and bumps. It looks wild and horrible, but trust it - it is for the most part a really nice run down all the way - here and there you find a trod and lose it again. And a lot faster than the path
CLimb to catbells. Go down the first section of rocky then swing sharp left down steep heather / grass. It looks bad, but it is really grippy and springy under foot. Go down as far as a diagonal trod that goes all the way down to the path that you started on.
But the reall secret is how to get down from dalehead.
Less than 6 mins all fast running to the tarn, if you know where to go....
Hope this helps