Hi, im the friend having the same issue that OP mentioned.
I´m having the same problem since day one. A few things I noticed.
-It only affects the game client.
-The ammount of time it last seems to be around the same always: 2-3 seconds, max 5
-If dual clienting, only happens to 1 client at a time.
-Its similar to the rubber band effect but not exactly the same, in the afore mentioned you can se the char moving forward and backwards and all the damage taken or effects activated will be shown at the same time. In this one the client will skip all movements, castings and damage taken and just update when unfrozen. Think of it like having VERY LOW FPS
-The client freezes completly, cannot write, cannot see other people moving, cannot use skills or move.
-It doesn´t have a pattern in the freezes, is completly random while playing.
-If a new visual effect (like for example a storm gust casting or magnificat casting) that wasn´t comes into our screen it wil trigger the freeze, but ONLY the first time. A new cast of the same or new skill wont trigger it as long the caster is already in the screen. Leaving and re-entering the screen also wont trigger it.
Things already tried and did´nt work:
-Running the programs in Admin. mode, running directly throug exe, disconnecting EVERYTHING else from the internet so it wont consume Bandwidth, closing all running programs barring the client. Tried every option in the config menu of the client. running the client in compatibility mod for older windows. (I have Windows 10)
Also I don´t use Steam, my best guess its a matter of compatibility with the Video Card or the OS. Got a Nvidia Geforce GTX and an i7 processor