Over a year ago, I married a woman from Belarus. We submitted her green card application in the United States. She wants to go home for a visit but cannot because she's afraid of missing her green card interview. Is there some way we can speed up this process?
You might as well ask whether you can make the earth move faster around the sun. Government bureaucracies, like planets, operate according to their own natural laws. They tend to move slowly, and they don't take kindly to questioning or prodding.
However, you should check on what's a normal schedule for being called in for interviews in your area. Do this by going to the government website www.uscis.gov and entering your application receipt number under "Case Status." That will tell you whether your case is still "pending," and how many months is normal to wait in your area.
If you've waited longer than other people, make an INFOPASS appointment to visit your local USCIS office. Bring your receipt, copy of your application, and any other relevant materials.
Even if you discover that your case is on a normal time schedule, here's some good news: The longer the wait (and the average wait is several months), the more solid your marriage is going to look by the time you reach the green card interview.
The two of you can use these months to improve and prepare the evidence of your bona fide marriage that you'll bring to the interview: copies of shared home rentals or title, joint health insurance, car insurance, credit cards, and more. If these requirements are new to you, see Nolo's Fiancé and Marriage Visas: A Couple's Guide to U.S. Immigration, by Ilona Bray. It covers everything talked about here and more.