Performance question for app script

[esamb...@gmail.com]

I have a time-triggered script running daily that trashes and then rebuilds (with complex permissions structures) as set of over 35 documents.  Most of these documents do not change on any given day, but for security reasons, I can't allow any document link to last more than one day.  SO .. I rebuild every document every day, reapply all permissions, and I think I am about to blow the limit on app script execution clock time.

Can anybody suggest an alternate document upgrade cycle?  I thought of copying the docs rather than rebuilding, but I can't figure out how to keep permissions on copy.  I think that a large part of the time needed is for permission setup using the Drive API, anyway ...