With rFactor2 we now have 3 types of lag to look out for instead of 2. With the sophisticated physics model in rFactor2 it places a heavier load on your computer system.
The three types of lag are:
1) Internet connection
If you think you are having an issue with any of these things it can sometimes be tricky to determine which one, or what combination of these things are causing the problem. Fortunately rFactor2 includes some tools to help you figure it out. Also there is a website that will test your computer and give you a report of how good it is. It can be found at http://www.userbenchmark.com/Software
1) Internet Connection - If you see cars blinking out, high ping numbers when you press the tab key and see the driver names over their cars, cars moving sideways or sinking into the track, then you're having Internet connection problems. You could just be having a bad connection that night or may have something running in the background that is using up your connection.
Solutions: Make sure all cell phones at your house are not set to WiFi when at home, or your wife and kids aren't downloading or streaming anything, like movies or music. Make sure your computer isn't downloading an update or anything else that uses bandwidth. If you have Windows 10 Home Edition it will randomly update itself and there is no way to shut that off without doing Registry hacks. If this is the problem and you're not comfortable working with the Registry then ask for help.
2) Graphics and Video Card - this one is a little easier. Press Ctrl-F when racing and it will tell you what your Frames Per Second (FPS) is. Anything higher that 80 or 90 and your fine. Anything less and you're in the danger zone. It may be fine now but more detailed tracks are coming in the future.
Solutions: Turn down some detail in rFactor2. Or buy a better graphics card. You don't need the latest greatest card so check for what's on sale and do some research. Ask for help if you're not sure what to do.
3) CPU - The default keystroke to check this while racing is Ctrl-J. For some people it may be Ctrl-C. If neither works then under Settings, Misc, look for CPU Time and see what key is mapped to it. This will show a graph while driving that has a green and purple bar in the top right corner. The Green bar is for Graphics and should always be pegged. The Purple bar is for physics and should be less than 3/4 of the way accross, otherwise you're in the danger zone. The shorter the better. You may only experiance a problem in the corners with other cars around you and you will see them jump forward and backwards but they'll be fine on the straights. Your car can develop a sudden and severe push in the corner where it seems like it wants to go straight or head towards the wall. Or you may not see anything wrong but no matter how hard you try you're half second or more slower than everyone else and noticably slower online than offline. This is because the CPU gets maxed out with cars around you and your car slows down until the CPU catches back up.
Solutions: Turn off all background tasks in Windows. A program called EndItAll is very helpful with this. Or upgrade your CPU and/or motherboard. Last resort is to overclock your CPU but this it NOT recommended unless you're comfortable with the inner workings of computers and are willing to take the chance or burning it up.