#2351 Finer-grained timing shows that element writing is least-scalable.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18242 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2351 Avoid deadlock in uninstrumented writers

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18243 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2351 Oops - the matching half of r182432

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18244 b5f69653-2bf5-0310-8201-b0dafb8e1405