Read a PlaceHolder without postback

Dear all,
I create a web site containing a placeholder where I dinamically insert a matrix of textboxes by code:

i.e.:

TB1.1    TB1.2    TB1.3   TB1.4
TB2.1    TB2.2    TB2.3   TB2.4
...
...


I activated the "AutoPostBack" to these textboxes.
I added:

AddHandler MyTextBox.textboxEvent, AddressOf getMyEvent

to the textboxes.
This event is bound to TextBox.TextChanged event

So, when I change the value in a the textbox, the getMyEvent method is called.

The problem is that every time I change the value in the textbox, all the web page is reloaded (postback event is triggered).
The page refresh required 2/3 seconds, so I'd like not to refresh the page at avery textbox change, but only when I press a Submit button (asynchronous update).

The problem ...