  We analyse the mixing profile of a random walk on a dynamic random
permutation, focusing on the regime where the walk evolves much faster than the
permutation. Two types of dynamics generated by random transpositions are
considered: one allows for coagulation of permutation cycles only, the other
allows for both coagulation and fragmentation. We show that for both types,
after scaling time by the length of the permutation and letting this length
tend to infinity, the total variation distance between the current distribution
and the uniform distribution converges to a limit process that drops down in a
single jump. This jump is similar to a one-sided cut-off, occurs after a random
time whose law we identify, and goes from the value 1 to a value that is a
strictly decreasing and deterministic function of the time of the jump, related
to the size of the largest component in Erd\H{o}s-R\'enyi random graphs. After
the jump, the total variation distance follows this function down to 0.
