Can you do a little investigation for me as your having this issue, want to see if the problem is page related like I get from time to time.

Open several browser windows, do a bit of browsing in each and leave them open. When unlocking, and device "hangs", check in top to see if you get very high usage from browserd. If so, does it remain high? If yes, close one window at a time and check top to see if usage drops.

I find there is usually one window which is the cause but haven't worked out the definitive cause yet.