According to the Department of State, sequestration will likely reduce the number of officers processing visa applications, which will negatively impact wait times at U.S. consulates.
Department of Homeland Security will be affected as a whole, but many agencies within DHS will be impacted more than others. For example, Immigration and Customs Enforcement (ICE) and Customs and Border Protection (CBP) are among the agencies hardest hit. This means that there will be lower numbers of agents, airport screeners and border agents on duty, which will affect waiting and processing times. While USCIS is also to lose funding, most of its budget comes from fees collected for processing petitions and applications, so the impact to USCIS should not be as significant compared to other agencies. However, if CBP has to furlough some of its workforce, it may take longer to cross through border posts and more difficult to obtain immigration-related benefits by CBP such as I-94 processing