As there are already multiple threads about lag and connection issues we are closing this one. You can continue discussion and find troubleshooting in the thread below.
The first two troubleshooting steps we recommend for this issue is repairing through the launcher and disabling add-ons. If you are still freezing after these steps please let us know.
There are some other basic crash troubleshooting steps to try that may help with this freezing. In particular you should try removing any add-ons you have loaded.