This book describes the performance issues related to Fine grained permissions like Item level permission, column level permission and folder level permission in SharePoint Lists.
This book also explains the best practices that has to be followed while planning for Fine Grained Permissions (FGP). Although this book in for SharePoint 2010, I don’t find any difference in terms of max numbers applicable for list items and columns.
Check out the previous book which provides information of maximum limits and thresholds of SharePoint 2013 objects. The topic Security Scope under List and Library limits provides you the information of Fine Grinned Permission level for Item level security in SharePoint 2013.