pfSense » pfSense Plus

I have used pfsense CE for about 5 years. Finally on December 2021, I acquired a pfsense plus machine: Netgate 1541. I started configuration from zero and it works smoothly. At the moment the only "bug" or whatever to be is when trying to load the DHCP leases from STATUS menu, it lasts a lot of time to show or gets a 504 gateway error. I found in this forum and other one that removing old files (dhcpd.leases and dhcpd.leases~) correct the problem. Temporarily it works but after a few minutes, it hangs again. I checked all options and configs I realized but i can't find out what is triggering this problem. I have one WAN, LAN and 10 VLANS, all of them have DHCP enabled. Globally I have about 2000 of 4600 max possible leases.