Not my work, just a copy/paste:
"The S meter is actually "skew", not "strength". It measures the simulation-time difference between your computer and the server.
The most likely scenario is that the S meter grows and grows. As it gets larger, cars around you likely start to move more erratically. Eventually they all disappear. Not long after this, the screen is likely to flash, the S meter returns to "zero", and the cars shortly reappear. Or, as the S meter continues to grow, you may be disconnected.
The typical cause of this behavior is that your computer has become overloaded - it no longer has enough compute power to advance your simulated world quickly enough to keep up with real-time. This is more likely to happen in Race and Practice sessions when there are many other cars on track with you. Your computer has to receive more information from the network for these cars, it needs to move these cars around in its simulated world, it needs to draw these cars on the screen, it needs more graphics card memory to store their paint schemes, and it might need to mix more sound samples so that you can hear them.
Any settings changes that reduce this extra work load are likely to help: - On the options/graphics screen, reduce the Video Memory setting. Often times the setting can be high enough that some of the computer's memory is used in addition to the memory on the graphics card itself. When needed, texture maps are transferred from the computer's memory to the graphics card. This is slower than when the graphics card just uses its own memory. Note that the number that is displayed is the amount of memory that the sim will use for texture maps and such, so this number would need to be lower than the actual amount of memory on the card to prevent this system<->video card texture swapping (some graphics card memory is needed for the display itself, along with other things).
- Reduce some of the detail and/or quality settings on the options/graphics screen. Many of these settings not only make your graphics card work harder, but also make the CPU work harder to feed it the extra data.
- If you have edited app.ini and increased the number of sound streams that are mixed, reduce it. "