Upgrade to EPiServer.CMS.Core 12.13.1 as soon as you can
Our general recommendation is to keep up to date to latest versions if you can. Outside of new features, it usually contains latest bug fixes and general performance improvement.
CMS.Core 12.13.1 contains two important/critical bug fixes - discovered and fixed by my colleague Magnus Rahl. More details can be found in the release notes
Those bugs are especially relevant when you are indexing your content, using Find - as you would be loading a lot of content and then serializing them into JSON objects, leaving a lot of cached items in process. Those can hog memory indefenitely and the only solution would be a restart (if the instance does not restart by itself via AutoHeal). The bug fixes allow cache items to be properly trimmed, and garbage collected, so memory is freed.