Max,

That's a reasonable class hierarchy. The performance really doesn't degrade that fast with depth of the tree. There is virtually 0 hit for levels where there is no method code. You want to just make sure that you have optimized code where you do have in the hierarchy. Methods of a form to worry about most are Load(), Init(), Activate() and Refresh().

>I'm going to write my own form class
>

>and organize them as (fox)form-->_mybaseForm-->DataInputForm --> DataInputFormForAAA
>                                                             --> DataInputFormForBBB
>                                                             --> ................

>
>But i'm worry about the running speed of it.
>
>Please tell me some of your experience, about the speed .