Don't know what to tell you. Some WU's here do take a long time. I'll check my boxes because several look for work but over the last few months I've done several WU's and I'm not aware of excessive times to complete. By excessive time I mean several days I mean 4 or more days. Earlier this year there were some ugly ones though.
I have a personal (unsubstantiated) belief that the Lattice WU's complete faster if the PC is only used for crunching and if only Lattice is the only(main) project running. If Boinc or the PC is splitting time with other activities, the Lattice WU's take longer to complete.