On March 20, 2017, Microsoft released SQL Server 2016 Service Pack 1 CU2, which is Build 13.0.4422.0. This CU has 101 fixes in the public fix list, by my count. This is a pretty large CU, and if you look at the fix list in more detail, many of them are for pretty significant issues with AGs, columnstore indexes, and general performance.
Here are many of the more interesting Engine fixes:
FIX: A memory leak occurs when SQL Server procedure cache consumes too much memory
FIX: Assert memory dump on a mirror server in SQL Server
FIX: Queries that run against secondary databases always get recompiled in SQL Server
FIX: Significantly increased PAGELATCH_EX contentions in sys.sysobjvalues in SQL Server 2016
FIX: No automatic failover after database mirroring stops unexpectedly in SQL Server
If you are running SQL Server 2016, you should be on the Service Pack 1 branch as soon as possible. If you are on the SP1 branch, then you should make an effort to be on the latest Cumulative Update as soon as you are able to complete the planning, testing and deployment process. Nearly a year ago, Microsoft changed their guidance about deploying CUs. Since then, Microsoft recommends ongoing, proactive installation of CUs as they become available.