You must know that the game NOT execute the scripts in constant way. The game ONLY execute the scripts for a specific time each frame.
The game works in frames per second and normally you have 60 FPS and that mean the game draw the screen each 16.66 miliseconds.
In the [Papyrus] section of Skyrim.ini the game have the configuration about how many miliseconds must execute the scripts.
The default configuration is 1.2 miliseconds and some developers recomend put it to 1.6 miliseconds.
This means EXACTLY that the game ONLY executes the scripts during that time in EACH frame.
If we substract 1.2 or 1.6 from the 16.66 miliseconds we get 15.46 or 15.06 and the game must create the frame in this time or less for have 60 FPS.
Normally, that's enough time. If you do not have 60 FPS, check your graphical configuration or your ENB.
If you use the math 1.6 it is near 10% of 16.66. That can NOT justify a low framerate.
Using a little more math, a second is 1000 milliseconds, at 60 FPS the scripts run ONLY for 72 or 96 milliseconds.
That's less than 10% of every second.
In some web pages, it is recommended to place the parameters in 800 milliseconds and make a small calculation, which is 80% of every second.
That means that the game can spend 800 milliseconds in creating an image, while the scripts are running, and you can have exactly 1.2 images per second.
You can go a little further and put the value in 2000 and you will have an image every 2 seconds or what is the same, 0.5 FPS.
You can edit the parameters in the [Papyrus] section of your Skyrim.ini and run my test to perform your own verification.
Using normal values of 1.2 or 1.6, the game only executes the scripts for 96 milliseconds or 10% of the time of each frame.
And what does it mean? Yes ... you have the answer ... the execution of scripts can not affect the frame rate or game performance.
When a game has problems, they are usually caused by the installation of the mods. Probably due to an outdated mod or collision or a bad dependent mod.