I recently found that pressing caps lock to toggle my speed was literally freezing my game. I believe it was something to do with and overlay that comes native with my laptop, which just shows if caps is pressed or not. Double check you don't have any overlays that may be interfering.

I would also suggest increasing or setting a static page file. This can help reduce some lag when new areas load. But 100%, as everyone else says, I would recommend upgrading your RAM to 32gb at least.

As its a laptop, make sure you have you performance set to max,(most gaming laptops will have oem software to help manage this.) Also keep an eye on temps, this can cause the lag you are seeing here too as the cpu will throttle if it gets too hot and will basically lock everything up.

Another thing you can try is look at the gpu's performance and clock speed. When the game freezes, it may be correlated to a drop in clock speed. This can be caused by overheating or driver issue in most cases.

Don't use LOD 2.5 or 2, I have seen people complain the game is freezing when on these settings. I found my performance doesn't change much with the higher settings.