How to Disable Comment Limiting in WordPress

First off, you should be familiar w/ PHP. If not, don't screw around because you could break your WordPress installation. If you have a nominal amount of functional programming experience, you're probably fine.

Locate the wp-includes directory in your WordPress installation. There should be a file named comments.php.

Jump to somwhere around line 935 and you'll fine the following function:

function wp_throttle_comment_flood($block, $time_lastcomment, $time_newcomment) {

This function can basically do two things:

1. Disable Rapid-Comment Checking altogether
2. Determine the Acceptable Interval Between Comments

As you can see from the comments in comments.php, this function will return the following:

 926  * Whether comment should be blocked because of comment flood.

So, if you want to disable the comment limiting check altogether, make it return false in the very first line of the function:

return false;

Otherwise, if you want to make it so that your users can comment faster, jump down a few lines to the following:

  if ( ($time_newcomment - $time_lastcomment) < 5 )

The value of 5 I have is the interval. So, you can read this as the following:

If people are leaving comments within 5 seconds of the last comment, then the new comment will be considered spam.
I believe the default value here was 45, but my users liked leaving rapid-fire comments, so I brought it down to 5.

That's about it, I hope you have fun hacking your WordPress installation.