Today when i was working on the new update i stumbled across something that could be one of the troublemakers for the low fps.
This will not solve the client speed for windows 8 and specially windows 10, this problem is a lot deeper and will require almost a complete rewrite of the graphics engine. Directx7 and Direct Draw are no longer supported, but updating it is not that easy.
However, this small change in the render distance already makes a huge difference and it should no longer drop your fps below 10 within 30 minutes.
Because this is a important thing, i didn't want to wait until the update is finished to patch it.