It takes about a minute for each member, and if I try to batch approve/decline, I get a 500 error. I'm using 22.214.171.124 on dreamhost on a MySQL 5 database.
Sounds like you need a better host.
This occurs on some hosts when they enforce a "process limit", I as suggested move to a host with less restrictions or host the website yourself on a dedicated server or vps.
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