I think I answered your question.
You never said what version you were running.
The index drops were not the only changes. There were several changes to done with work being done alot on the online table.
If you want to increase performance turn off the who's online. If you have large amounts of thumb displayed in the thumb blocks cut these down.
If you have hundreds of cats and they are showing alot. Try decreasing the cat depth so only parents will show or the first 3 levels