Proved beyond doubt that
get 'new/(:a)/(:b)/(:c)/(:d)/(:e)/(:f)/(:g)/(:h)/(:i)/(:j)/(:k)/(:l)/(:m)/(:n)/(:o)/(:p)/(:q)/(:r)/(:s)/(:t)/(:u)/(:v)/(:w)/(:x)/(:y)'
as proposed by a technical guy who interviewed me makes the app unusably slow. With that route pointing at "new#an_action",
get  "/new/foo/bar/fubar/snafu/snafu/situation?situation=normal"
takes over seven minutes. Then again, I don't have a supercomputer.

See get_test. Set environment variable OPTIONAL_PARAMETERS to 1, then run 'runtests.sh' to see the proof.