I know me putting my input in here isn't really going to help anything out but I'm going to share my FPS and specs anyway.
FPS test during day/Afternoon on Sandy Shores Runway. All at same time, weather, and on or next to Sandy Shores Runway. (Avg. is just the general area where the fps would stay at, not an exact average of the fps)
FPS without LSPDFR loaded: 61-112 fps. Avg. 75 fps
With LSPDFR loaded: 61-78 fps. Avg. 68 fps
On Duty (on foot): 51-71 fps. Avg. 60 fps
On Duty (in stock gta police car): 50-68 fps. Avg. 60 fps
On Duty (ELS police car): 43-60 fps. Avg. 50 fps
In Pursuit (2-5 police backup in stock gta cars): 50-63 fps. Avg. 55 fps
In Pursuit (2-5 police backup in ELS cars): 43-58 fps. Avg. 53 fps
In conclusion: I lost 8-20 fps when I load LSPDFR, around 8 fps when I go on duty, 1-2 fps on duty in stock police cars, 10 fps in ELS vehicles over stock police cars, and 3-5 fps in a pursuit when using ELS vehicles over stock. Sometimes I will get random frame drops while patrolling bringing me down to 30 fps but these only happen once every 5-10 minutes.
My Computer Specs: i7-7700k intel processor, RTX 2070 8GB DDR6, 16GB DDR4 of ram, and I'm operating on Windows 10.
I know my cpu isn't that good for GTA V but it is still able to run it alright at max settings 1080p which I used to test the fps earlier. Hopefully some of my info will be helpful in someway or another. If you want anymore information like my exact GTA V graphic settings or other stuff don't be afraid to ask. I'm really enjoying LSPDFR 0.4 so far and my only problems that annoy me at the moment would have to be when you install Computer+, LSPDFR will crash if you ask a pedestrian for their ID. Stop The Ped is really buggy/crashes a lot. So I'm not able to do breathalyzer tests, call to truck, etc.