Currently, expanding is immediate, but collapsing takes time.
This is because each row has a different height, and the javascript animates the "max-height" property. A better solution might be to use the jQuery slideUp function.
Collapsing and expanding now use slideUp and slideDown and are faster to execute, but I'll keep this issue open because even with that, collapsing the last step of a long proof still takes a lot of time on my browser.
Currently, expanding is immediate, but collapsing takes time. This is because each row has a different height, and the javascript animates the "max-height" property. A better solution might be to use the jQuery slideUp function.