More simply, the original ULib (and the admin mod for ULib's group access controls, ULX) was never intended for so many 'jobs' or 'teams'.
It's meant primarily for a select few special trusted people to maintain a server, act as the server's police so to speak, in a few special groups.
Unfortunately for it's design, but fortunately for fans everywhere, due to how easy ULX is to maintain custom groups and users versus the lack of understanding of many of differences between 'group' administrative control and "team/job/role" access, many use ULib far beyond it's original purpose and make (too) many groups and add (too) many users to all those groups as "jobs".
We're looking towards the future, but the challenge still remains the same.
Jamster, back more on topic to your original question, how large are your /data/ULib users.txt and groups.txt?
How many users and groups do you have?