My Network: toni-english.com is in very good shape. No problems (post W3 Total Cache plugin)
-MultiSite network with 6 sites – all mine.
-I have 170 plugins, activated a only few per site.
1). Main Site: 70+ pages, lots of imported content via RSS, occasional network crossposts, YouTube channels/playlists embeds, import auto-post from a WP.com blog. And content.
Other sites are very small:
2). One site managed by plugin Memphis Documents Library 500 PDFs docs. https://wordpress.org/plugins/memphis-documents-library/
3). One site bbPress for writing practice
4). One site simple static content of English lessons.
5). One site has plugins active for creating/administering quizzes and word puzzles.
6). One site simple blog for my class prep