I did a major rewrite of block and transaction handling yesterday, both on the backend and the frontend. The backend part meant I had to rebuild the block and transaction database from block 1. I noticed this morning the latencies are really high, I'm guessing it's due to the database rebuilding overloading the server, making the client fall out of sync a little. If the latencies don't fall during the day I'll look into it when I get home.
The rewrite was to handle transactions and fees in assets other than BTSX, as well as adding the possibility to browse through all the blocks in the overview page. I still have to check it some more for bugs, but should be available this evening or tomorrow.