I think we might need a pause on immigration for 20 to 30 years. I don't think we have enough assimilation lately. The purpose of immigration is to benefit the existing American society. When we see protesters holding foreign flags, ballots in foreign languages, and thousands of refugees being brought to America who have hostile views of America, it is obvious that something is entirely wrong. At the very least, what we should consider doing is repealing all of the existing immigration laws (which would not allow any immigration) and starting from scratch and determining who we, as a people, believe should be allowed in. Congress has complete discretion on who we should allow in.
Further, allowing a lot fewer people allows the so-called screeners to have more time to evaluate who we are bringing in. I don't have much confidence in bureaucracy, but if you're bringing in millions of people, by definition, I am sure we're allowing in a lot of bad apples because there is no way to know who is really coming.