If you use unrealircd channels modes +f and +j can effictively protect against the three this script does.

/mode # +j 5:20
would allow any single nick join 5 times in 20 seconds. this prevents revolving doors or join/part floods
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/mode # +f [20j#i5,70m#m2,15n#N5]:15
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:15 = In 15 seconds
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20j#i5 = 20joins in :15 seconds leads to +i invite only for 5 minutes
this is helpful against a mass join flood.
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70m#m2 = 70 channel messages in :15 seconds leads to +m voice only for 2 minutes
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15n#N5 = 15 nick changes in :15 seconds leads to +N no nick changes for 5 minutes

You could also use +f [20j#R5]:15 which set mode +R instead of i. this would allow registered users only to join.