One thing that can cause a delay is that your site may be large and you only have 1 childweb. You might consider breaking your site down into more childwebs so that each web has less to process. The /reguser childweb only contains a small amount of the files on your site, and the <Root Web> has to work twice as hard to process any information. As the site grows, processing the form will continue to get slower and slower.
Also, if the form is quite large and is going to both an e-mail address AND a text file, This can also slow the form down.
Try putting the form in its own subweb, and you might want to consider sending the form results to an e-mail address OR a file. This should speed things up significantly.