Avoid drawing hidden `TreeView` items

data/plugins/treeview.lua

@@ -366,16 +366,19 @@ end
 
 function TreeView:draw()
   self:draw_background(style.background2)
+  local _y, _h = self.position.y, self.size.y
 
   local doc = core.active_view.doc
   local active_filename = doc and system.absolute_path(doc.filename or "")
 
   for item, x,y,w,h in self:each_item() do
+    if y + h >= _y and y < _y + _h then
       self:draw_item(item,
         item.abs_filename == active_filename,
         item == self.hovered_item,
         x, y, w, h)
     end
+  end
 
   self:draw_scrollbar()
   if self.hovered_item and self.tooltip.alpha > 0 then