In reply to mountain.martin:
Bits but I don't think by much.. the scree sections have changed.
Often in those days sheep densities were higher so grass was much shorter, its why a lot of the classic snowdonia records don't get touched..
There is talk to totally change the route, prevent short cuts, even use a different start location due to traffic/parking which will be sad.
Kenny's snowdon race record is now untouchable as the course there is a lot slower than it was..
Also routes like the peris horseshoe short cuts are banned now so the route is a few minutes slower for those reasons.