D7.9 introduced 404 fast paths which don't fully bootstrap drupal on 404's for certain file types if it's enabled, thus saving some bandwidth / computation. More info is available here: http://drupal.org/node/1296384

By default this excludes only certain file types such as .jpg, .txt., etc., looks like this:

    $conf['404_fast_paths_exclude'] = '/\/(?:styles)\//';
    $conf['404_fast_paths'] = '/\.(?:txt|png|gif|jpeg|css|js|ico|swf|flv|cgi|bat|pl|dll|exe|asp)$/i';

I want to use this for all paths. Are there any repercussions to that?

I tried changing it to 

    $conf['404_fast_paths'] = '/*$/i'; 

However, this returns a warning:

> Warning: preg_match() Compilation failed: nothing to repeat at offset 0 in drupal_fast_404() (line 2484 of /cms/main/includes/bootstrap.inc).

So what should the syntax look like up there to both work and not generate a warning?

Alternatively, if there isn't a solution to this specific question, is there a way I can speed up 404's for all Drupal pages, would it better to use the Fast 404 contributed module for instance?