Hmm. Odd. I'm running smooth as silk. Perhaps give it some time if you have a lot of contacts, chats and channels that get updated. If not delete and reinstall it maybe will cure you. I would give it some time if you do have a ton of contacts and chats. I don't so it lagged at first but loads up perfectly now.
Seems ok on my Z10. Everything seems to load as it did before and the keyboard appears and disappears and it did before. As for laggy, haven't really had a chance to see. Will continue to monitor as the day pregresses.
As with previous updates - if you have too many open chats, and chats that are too long, performance can be affected. I've had it laggy too but the moment I cleared all chats, closed and reopened the app, it runs perfect.