GXT3.0.1, Chrome 32, windows 7 x64

I have a grid with a GroupingView, if i enable the grouping
view.groupBy(myColumn)
before the data (max 2500 rows) is added to the store the browser gets frozen for a very long time (never had patience to wait till it actually completes)

if i enable grouping after i add the data to the store than the grouping part is freezing the page only for 5-6 sec

now the problem is that i add and remove data from time to time, and each time i need to disable grouping
view.groupBy(null) change the data in the store and than enable grouping again , disable grouping takes also ~5 sec

bugs:
1) enabling grouping before data is added to store generates a performance problem
2) adding data to a store for a view with grouping has a big performance problem

workaround:
1) enable grouping after data is added to the store
2) disable and re-enable grouping when data is changed in the store (~10 sec of hang time not really acceptable)
3) maybe remote grouping/paging ... will help (did not tried it yet this will be my next step)