Fantasy, this happens to me as well. My issues happen in the Spa, the Island and Spacies (so far). Sometimes I'm invisible like you pointed out. I know I'm there, as I can talk and move (even point my mouse at a chair and probably sit - as I have that option), but my avatar is invisible to me. These rooms take FOREVER to load. Trying to play an arcade game is impossible.
I tried SW for the first time yesterday, and the lag was terrible. I had no problems whatsoever until they rolled out this new update.
Although the items and changes are cool ~ extremely too laggy for me and my computer.
One thing I can point out is this ... I logged on well after 2am my time. The game ran much better than at peak times for me. I'm thinking part of the issue is the amount of people logged into the game. Just my 2 cents, but I noticed a huge difference.
Unfortunately, I can't possibly play every day after 2am just to escape the lag monster!