Re: BBpress faster than WordPress
More queries in WordPress vs. bbPress?
You can add this to your template footer.php (one for WordPress and one for bbPress) files and it will add a comment that is visible in the source with the amount of time taken and how many queries it took to generate the page.
<!-- It took <?php bb_timer_stop(1); ?> and <?php echo $bbdb->num_queries; ?> queries -->
<!-- It took <?php timer_stop(1); ?> and <?php echo get_num_queries(); ?> queries -->
Maybe you can spot some differences there.