Hi, I am not sure why it would be dropping your FPS so much with so few lights, I have a test map with 120 lights with no issues. Can you open up the dev tools, switch to the Performance tab, click Start Recording and then wander around in the laggy map for around ~10-15 seconds and then click Stop Recording and show me the results in the Bottom-Up tab?
Edit: Since performance testing is a little tricky and may require quite a lot of back and forth testing, you can also come into my Discord for help, it would probably be easier to troubleshoot than itch.io comment section.