Hello,
I discovered that dashboard page (when firewall log widget is activated) & firewall log page are verrrryyy long to load when it is requested to display log on an interface that has no entry in log.
In my case I have many entries logged for LAN and OPT1 but none for WAN (behind another fw) => if i try to display / filter firewall log entries for WAN it takes several minutes before displaying web page.
nota : "cat /var/log/filter.log | grep vr1" provides an instantaneous (and blank) answer.
Best regards.
I've added a ticket, thanks for the report: https://github.com/opnsense/core/issues/672
Will look at it after 15.7.25 is out.