[Critical] Extreme lag / performance problems on UEFN islands with creatures & wildlife while building enabled

Thank you for your help!

Although it is 5/10/2024 and I got a Publishing rejection saying my map is not 30fps, and players reporting this. However when I test on my ps4 and pc it is running 100 fps on TSR Epic and Full Nanite settings turned all the way to EPIC. ps4 bounces 60fps to 120 fps.
I am not sure what is causing lagging for other users and I gaurantee there is a bug.

Please can you help?
All my textures are 512 x 512 to 1024 x 1024 at the most! Please help ???