ISA site and content rule

Hope you all are doing fine. I'm having a problem in my ISA server
from the last 2 weeks. I have created many SITE AND CONTENT RULES in
my ISA server to restrict users view specific websites. Whenever these
rules are enabled; ISA client (on Client machine as well as on ISA
server) refreshes very very late, which is causing choking of a
network and slow internet. But if these rules are disabled, ISA client
seem to work perfect but my internet doesn't(due to small bandwidth).
This issue could be a configuration problem but i have not changed any
configuration from the last 6 months.
Please help me out in this problem.

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