Opedirectoryd taking >90% of CPU + thousands of messages in console per second
I've got an answer to this problem for people coming here with this issue who aren't using Active Directory (meaning that it can't be the cause).

For me the problem was my Dropbox was struggling with broken symlinks inside my Dropbox folder. I had about 20-25 of these broken symlinks. You can see if this is the problem for you by whether the problem goes away when you quit Dropbox (and wait a bit for the Activity Monitor to calm down).

You can see the location of these broken symlinks with:

cd ~/Dropbox
find . -type l ! -exec test -e {} \; -print


If you want to then delete these (they're broken after all, just get rid of them), you can run this:

find . -type l ! -exec test -e {} \; -print | xargs rm


I quit my Dropbox program before doing this. After turning it back on, the problem was gone!

Note: I ran this with gfind instead of find, which is the GNU version of find that you can get by doing brew install findutils. It should work perfectly fine with regular find though.