ExtJS Grid with 5,000 rows

Please take a look at the picture. We need a simple ExtJS app having two windows, each having a grid. Both grids are attached to the same data store. The store constains 1,000 to 5,000 rows, and around 10 columns. You can create a store of your own, having dummy content. Grid in window 1 only shows 4 columns, grid in window 2 shows 7 columns. "Name" and "Age" are editable in both grids (row editor). The user can seach the grid's "Name" column in the second window. Now what is of interest for us is performance. Please try to optimize the speed of the grids, so there is no big delays, when switching between the windown, scrolling etc. Please use Sencha's MVC structure for this app. Please mention "SpeedGrid" in your application.