ULX is written to be optimal.
Due to the way ULib stores users, the only performance issues we've ever seen commonly are
a) if people store too many users in various groups
or
b) the host has really poor I/O/extreme high latency for disk read/write.
ULib / ULX wasn't written to be a rewards system, yet some have written 'autopromote' scripts that give people low level groups after a certain timeframe.
The bigger the file grows, the longer it takes to read when people join.
Those are the only issues we've seen commonly. If you only have a few admins in your users file, then you shouldn't be having issue.
We've also seen addons cause conflict when ULib and or ULX was installed.
Without more detail, there are too many other variables.
