Hello,
furthermore you have to ask yourself, if it makes sense to apply such a long list to avast!. Usually you use third party tools for that and the URL blocker is right now more a nice feature for blocking single sites, when other users use your PC or to prevent some program from permanently accessing the same url, rather than a full-blown child/surf protection solution, where you could for example configure a list of users with fixed amount of time to surf on the web.
Malicious URLs are blocked by the network shield’s blacklist or by real-time scanning with the web shield anyway, therefore you may just exclude specific urls. At least at the moment…maybe avast! 7 will feature extended site-blocking features…