Glad to hear you've somehow managed to sort out your slowdown issues.
tkdiff wrote
I downloaded r2011b, but it's not clear how to install featool. Matlab states that apps using *.mlappinstall to install was introduced in r2012b, and will not work in prior versions.
Please try to follow the corresponding section in the
FEATool Multiphysics documentation and installation guide,
Readmes, and/or
previous posts/answers on this very subject.
tkdiff wrote
Windows updates, as they have a habit of doing, may make an older version of matlab unusable.
I do not have this experience at all, especially with Microsoft being as dedicated to backwards compability as they have been.