Fps is very broad unit of measure for your performance and means almost nothing to anyone. It also depends on your hardware, driver version. Also keeping engine open drops your fps while you try your game. You should learn how to measure what is really takes more time in newer version to solve this issue. Also keeping your lighting preview means light baking quality (and only decreases baking time), not your runtime performance.
Tech Art Aid channel on youtube has couple of videos on this topics. Here is my advice, instead of comparing engine versions performance, measure your performance on all topics and try to research about them. You shouldn’t take old engine version as reference, you should always try to measure everything and research why it takes so much time. Both for cpu and gpu. Maybe the problem is cpu and your ai, maybe it’s gpu, or culling problems. Or maybe upgrading your project breaks your lod references (i had this once, but i measured everything and realized lods don’t work). But if you don’t analyze your frames correctly, you will never know about the real issues. Also you should do it from time to time, so you can know what you can optimize in your game.
Performance changes comes from your content and how engine behaves to those assets. Engine behaviour can change from version to version, but also engine gives you a lot of tools to measue and debug your content, and how to change your content to new behaviour to get best performance.
Here is the link for Tech Art Aid youtube channel:
Start from watching Measuring Performance, GPU pipeline & bottlenecks, builtin profile and complete gpu stats guide and don’t forget to have fun.