goto=newpost is markedly slow after installing hack

the problem:
******
i just installed a hack on my forums. after installing it i have noticed that the goto=newpost action is markedly slow. it takes about 10 seconds to begin loading the page. when i uninclude the hack it's back up to speed again.

to clarify: the little image that precedes the thread title of a thread with new posts uses the goto=newpost action. when clicking this i experience the delay. the other instance of this problem is the 'Go to first unread post' link that appears at the top of each page of a thread that has new posts. when the first unread post is not on the page of the thread currently being viewed the 'Go to first unread post' link uses this goto=newpost action... again i experience an unusually long delay. of course when the page that has new posts is being viewed the 'Go to first unread post' link uses #newpost in place of goto=newpost which has no delay since it simply scrolls down to the appropriate marker on the page (all client side).

unfortunately i can't post a copy of the script for the hack because it's not my hack and the author hasn't released it yet.

i remember vbportal had this same problem a while back. i posted on phpportals.com to see if anyone knew how this was fixed in vbportal but my thread got deleted for some unknown reason.

related vars in vb scripts: search for $thread[gotonew] in forumdisplay.php and search for $firstunread in showthread.php
******

my question:
******
without seeing the hack... does anyone know of a possible cause for this delay?
******

thx in advance for any help or insight