For dictionaries I have 3 selected in Apple settings/general/dictionary:
2 English(US) (New Oxford American Dictionary, and Oxford American Writer’s Thesaurus) and the “Apple Dictionary”.
I have Marvin/General Settings/Dictionary set to ‘System’.
It’s strange because I’ve been using the “look up” a lot recently (mostly to prove to my wife that I’m pronouncing the words correctly

) and haven’t had it freeze up at all.