You need to be careful when using
ViewState
to avoid page performance issue. Also
ViewState
has a limit when it comes to size, so make sure that you don't store a huge amount of data in it.
As already suggested, you can use JavaScript/jQuery to add dynamic controls at the client. That way all interactions only happens at the browser, so you can have a fast response. Just google "adding dynamic textbox using jquery" to get more examples. Here's one I found:
How to add / remove textbox dynamically with jQuery[
^]