create and destory grid and store.load to fill will get slower at each iteration

[Gucky]

I am creating a tab with a panel and a grid inside it. It gets filled from the DB. The first time, its very fast, about 2 seconds. now each time I destroy the grid, remove the tab and than recreate the tab with the same grid, same data, the system slows down adding about 1 second. Using the profiler I can see that the number of calls within EXTJS increases by about 40000 ! on each create. The data are displayed within a second but the loading mask will not go for a while. This is the same behaviour in 4.1.0 and 4.1.1. Is that a known problem ?
According to the profiler, its the following piece of code that gets called thousands of times:
isModified : function( fieldName) {
return this.modified.hasOwnProperty( fieldName);
}

[scottmartin]

This should not be happening .. if you have autoDestroy set to the default true, this should be handled automatically.

Scott

[Gucky]

I have not changed any of the defaults, below a few lines of code if that helps:

......

        var overviewGrid = new Ext.grid.GridPanel ({
            id            : 'overviewGrid' + id,
            autoHeight    : false,
            autoWidth     : true,
            columns        : overviewColumnModel,
            store        : tomcatOverviewStore,
            loadMask    : true,
            features    : [filters],
            autoExpandColumn : 'managedBy'            
        });
       tomcatOverviewStore.load();     
   
        tabs.add({
            title        : recName ,
            id            : id,
            closable    : true,
            border        : false,
            iconCls        : 'icon-' + recKey,
            items        : overviewGrid,
            autoScroll    : true            
        }).show();    

        Ext.getCmp( id ).on( 'close', function() {
            releaseToolbar(); // Just deactivate some menu items
        });

.....
I could provide you with more details if you let me know what is useful to you