I recently downloaded FPS Booster Mod ( The Full version ) and it was amazing! It literally increased my fps from 10 to 30 sometimes even 40.
It must be mentioned that At the same time, I'm using "Ultra Level of Details" mod and medium graphics and "Speed Slider [v2]" and set it to %60.
The complete results:
*The FPS increased from 10-12 to 30-40 and when fully zoomed out of the city, 50. I believe this it would even be higher since I locked the fps at 50 because my laptop has a 48 Hz monitor.
*Before this mod, my laptop wouldn't get hot and Ram usage wouldn't go further that 4/5 GB. Now it's at 8 and my GPU and CPU is fully being used since I can't even touch my laptop. And believe me, as a laptop user this is my normal temperature when playing a game. I was always surprised when playing Cities Skylines and my lap top wouldn't get in any high temperature.
*Loading time didn't change a lot. I've heard that the loading time would get longer which in my case didn't. I also used "Ploppable Asphalt + [Loading time Fix]" mod which didn't made any change in my loading time. So in a nutshell, my case is a little bit weird.
*After playing for about 3 hours or more with the mod enabled, my game crashed 2 times. The game had never crashed before and I've been playing this game for a long time (not specifically on this account). So i think it's because of the fps booster mod?! I have the crash reports btw.
I should also mention that I use Loading Screen mod and my lap top has this specifications:
Lenovo Y50:
Inter corei7 4700
16 GB Ram
nVidia 960M 4 GB DDR5 (Always updated to the latest version)
HDD hard-drive
UHD 48 Hz Monitor (I run the game at 1920*1080 resolution)
and a fully updated windows 10
P.S. My laptop is 8 years old and the performance of my laptop has gone down the hill.

I hope this report is useful for the fps booster developers and thanks a million for the efforts to make the game optimized.