ListCtrl_edit 's last column is hard to edit

Hi all.
I use ListCtrl_edit code like the example in wxpython docs and demos.It has two Columns.i found the first Column that it could be edited easy,but the second Column,i enter A few characters and it took a while to display them,Sometimes the reaction is slow.The first column has no problem. I run the demo code( \wxPython-demo-4.1.0\demo\,it has the same problem.The last Column is hard to edit.
any suggestions?Thanks.