I personally think this issue is one of the biggest with this game. Reading a lot of the other threads where people are complaining, I think this UI lag is causing a lot of small things people wouldn't typically complain about in an MMO to be more obvious. If the UI moved faster, people would feel like they're working faster, getting things done faster, etc., and obviously, you actually would be.
As MasterOutlaw said, it definitely moves faster if you take your crafting elsewhere, rather than in the hoard of people standing next to the dude in the camps that you do leves for. That makes sense, so I'm wondering if maybe SE just tried to make the menu too fancy (semi-transparent, fading in and out, etc.) and it's causing it to run slowly. I personally could live without most of that. Like, in most games, it seems that the inventory/menus are just kind of images with interactive pieces/parts that get displayed to the user when a button is pressed, rather than the entire menu being an integrated/interactive part of the game. Seems like an unnecessary load.
As a side note, I noticed the recommendations for computers playing this game include an i7 2.66 gHz proccessor. How many people are actually running it with that? Mines a 2.6 gHz i5 and I have a monitoring system running when I play and I notice a lot of random spikes of CPU usage (upward of 80% load) at seemingly random moments. Maybe there's just something else in the game that's slowing down a little bit of everything and it's not just the UI's fault? Surely other people have noticed the slight delay in almost everything that gets done in the game, and I'd say it's not entirely fair to blame the game's servers for slow speeds (but still definitely a big deal).