Back to the matter at hand, I do not like mouse movement and cannot see where to turn it off in the game. The Option screen as well as some others seems to be porous to mouse clicks resulting in clicks on that screen moving the character, certainly undesirable. It seems to be in non-functional places such as between the arrow and the scroll marker in the scroll bar when the marker is at the bottom as well as the blank spaces between the option headers, actually pretty much anywhere in that pane which is not specifically part of the option name or its highlight. Oddly enough it does not happen in the pane where you change the settings. The same thing happens in the help window header pane as well and appears to happen in confirmation box windows too.
The grass has always been laggy but is not a really big problem for me.