I can’t tell you, but you can find out yourself if you’re currently using that mod: While playing the game, press F5 to enable debug view. Press F4 and make sure that “show-time-usage” is on. You might have to disable “show-detailed-info” and “show-entity-time-usage” because they might push the info you want off the screen. Press F4 to close the settings and then check the statistics on the left: The first number after “Update” is the total update time for your game per tick. Further below under “Script update” should be a line for “mod-Realistic_Electric_Trains_fix_balance_K2.” The first number after it is how much time is spend on the Realistic Electric Trains mod. Compare that to the total update time and you’ll see how “heavy” the mod is.
The Battery-Electric Train mod doesn’t show up under “Script update” because it has no scripting. Therefore, switching from Realistic Electric Trains to Battery-Electric Train will save you whatever time the Realistic Electric Trains mod is taking.
Example: To run at 60 UPS/FPS, the update time needs to be below 16ms. If your update time is 20ms and Realistic Electric Trains takes up 5ms of that, it means that Realistic Electric Trains is slowing down your game. Switching to Battery-Electric Train will reduce the update time to 15ms and your game will run without slowdowns. If your update time is already below 16ms with Realistic Electric Trains, you won’t see any difference at the moment – except that your CPU will run cooler – but that might change as your base grows. If your update time is 30ms and Realistic Electric Trains takes up 5ms of that, you would see a small improvement by switching to Battery-Electric Trains, but with an update time of 25ms your game will still slow down because your base is too big for your PC. ;)
Edit: If you’re currently using no electric train mod at all, I can’t tell you how much the difference would be. That depends on how big your base is going to be, how many trains you’ll use and how fast your PC is. All I can say is that the Realistic Electric Train mod (and all its derivatives) will always be slower because it uses a lot of scripting. The Battery-Electric Train mod will always perform the same as vanilla trains because it has no relevant scripting.
