Try either setting adaptative distance to a lower value or reducing the fps cap of your client to see if it works better.
I suggest you to try this:
Ingame,
go to options->graphics->details->fps cap
the default value should be 62.
Lower it to 30.
Save changes.
Run around and see if you notice any visual degradation (hopefully you shouldn't) see if that uses less cpu, and go to that region that lagged previously, to test it again.
Good luck.