The editor currently emits overly complex DOM fragments to represent an indent list. This can easily provoke OOMEs when performing a PDF export of the page containing such a fragment.
E.g. if you insert an (ordered) list in the editor, add and entry and indented it via tab the output will be a nested (ordered) list.
It is enough to place 22 tabs on the list item to cause an OOME if you export the resulting page as PDF.
My test setup was a vanilla 5.2.2 instance against HSQLDB with -Xmx1G -XX:MaxPermSize=256M.
Now I understand that this is really a problem of the PDF export (for which I'm going to raise a separate issue), but I believe the editor should make it an effort to use CSS instructions instead of DOM elements to reach the desired effect.