Query gets slow when bind peeking is turned on
Bind peeking is done in stages. First the query is be flagged as "bind sensitive" based on histograms, and then it may become "bind aware". The IS_BIND_SENSITIVE and IS_BIND_AWARE columns in V$SQL will show the state of the query. If IS_BIND_AWARE is not on, the query is not adapting.

This post helps to explains the process.