[Simon Lloyd]

banning by .htaccess is fine if you only have a few things in it because it is read with every single server request, so if you have 10 blocks in your .htaccess and lets say you have a web page with 30 elements (icons, css, containers, includes.....etc) then each one of those that tries to access that page has 30 checks made just to load that page.

Now consider your own landing page and check how many things load to make that page up and you'll soon see why having a lot of bans in your .htaccess can be detrimental particularly if you are on shared hosting or limited vps.

@Gadget_Guy & Max Taxable
The hook is style_fetch, you can try changing the hook for one of the others that loads before all the others but you may not see the result your looking for, doesn't hurt to try