TL;DR update: the options "Shadows" and "Shadow Blur" seem to be the cause of the stuttering in my situation. I've set them to "Low" and "Optimal" respectively. Seeing great performance gains and stuttering has virtually gone during the couple of races I did after changing the Shadow options. ======================================================================= I've been having some rather annoying stuttering issues during races lately (both offline and online). When this stuttering occurs, it doesn't necessarily mean my FPS goes down as well; it happens when my FPS is maxing out (capped at 60), but also when it's showing a dip (never going below ~45). I know it sounds weird, but that's the way it is. It almost looks like my FPS is between 3 and 5, but like I said, it never goes below ~45 whilst stuttering. The effect is noticeable while driving at specific points on different tracks, and most noticeably while driving through specific corners of a track. After some testing, I've come to the conclusion that the amount of visible vehicles is the only graphics/game options that has any influence on the stuttering being there or not. My specs are listed in my profile, but I'll write down the most important parts here: OS: Windows 7, 64-bit Motherboard: Gigabyte Z87X-D3H CPU: Intel i5 4670k @ 3.4 GHz stock (3.8 Turbo Boost) GPU: HD7970 3GB @ 1 GHz (stock) RAM: 8 GB DDR3 @ 1333 Mhz (stock) HDD: Samsung Spinpoint F3 1 TB (Windows installation) + Seagate Barracuda 1.5 TB (rF2 installation) both @7200 rpm Single Monitor: BenQ G2420HDB, 1920 x 1080 PC is running in the High Performance power plan of Windows Settings: literally everything maxed out, except shadows (medium). V-sync = on ("video" option), vertical FOV = 65, FPS capped at 60 through the .PLR file, HDR = on (automated), FXAA = on. All settings are done through rF2, I'm not using an AMD Catalyst Control Center profile. Things I've tried without result, before stumbling on the Visible Vehicles option: Setting v-sync at "software" and "GPU" mode. Completely turning off v-sync. Turning off FXAA. Lowering opponent detail. Lowering track detail. Lowering shadows. After trying the above without results, I came across the Visible Vehicles option on my to-do list. Before that, I had tried to set the "Extra Visible Vehicles"-line in the .PLR file to "15" (default was a staggering 105, btw), but to no avail. Anyway, the setting I had been using since the beginning for the amount of visible vehicles, was 25. I figured my PC was powerful enough to render them, but I guess I was wrong: when lowering this setting to 15 visible vehicles, the stuttering had gone! The magic number for my specific issue proved to be somewhere between 15 and 20, where 20+ means stuttering and 15 means no stuttering at all. Any number between 15 and 20 is a hit or miss situation; sometimes there's stuttering, sometimes not. I've tested it with two official ISI mods/tracks: Civic at Loch Drummond and Karts at Quebec (excellent mod btw, love it). Both of these tracks have one corner where the stuttering is most noticeable (read: obnoxiously annoying, to the point it impacts my steering-capabilities/reaction time, resulting in unnecessary spin-outs and crashing into other drivers involuntarily). Those corners/locations are marked with red in the pictures below: Loch Drummond/Civic: Quebec/Karts: When using 15 Visible Vehicles everything is fine, even in the red areas. Increasing this number means more stuttering. I've also checked the CPU-load in-game with Ctrl+C, and when I drive through the mentioned corners, the green bar shoots all the way to the right. I'm assuming it's under maximum load at that point. The green bar goes back to the left when I'm on non-stuttering sections of a track. Now, there are two reasons I made this thread; firstly I hope this will help others with tracking down any stuttering problems they have (I've seen more threads about this, but figured it was best to not hijack them). Secondly, I'm left with some questions myself after the findings above: 1. Is the stuttering with 15+ Visible Vehicles something I have to just deal with? If so, is it down to my CPU, my GPU or something else like optimization? 2. Is there anything I can do to get rid of the stuttering, whilst increasing the amount of visible vehicles (and thus the realism aspect of the game, imo) and keeping the high graphics settings? Apologies for the somewhat lengthy post, but if anyone has questions or suggestions, I'll be glad to hear them.