I think the big lag relies upon that the team is still approving accounts personally. It takes more time because they don't want to just verify your account/your email address but they also want that good content is posted on this site. This is especially important for the young age of this platform and I, therefore, think that it's good to take some time before approving/verifying accounts. Also, you have to consider that, if a "spammer" signed up, he wouldn't want to wait for days to be verified.