Shortly after Sage 50 2018 was released some users reported that drop down list, such as customers or items, were very slow to open. The problem is limited to very large lists. Sage has responded quickly with update 2018.0.1. Sage is recommending that only user who are experiencing the problem install the update, so I would not expect it to show up as an automatic update. But anyone who is experiencing this problem in version 2018 can download the patch here.