The game is not very well ported and many people have large performance issues (especially in Chemical Plant Zone). Thanks to BlackLionPT of the SPUF forums for the following guides.
Set resolutions with 60 Hz
In the configuration tool, make sure you select your resolution with 60 Hz, not 75 Hz. The game can not run smooth on 75 hz, because it's engine is limited to +/- 60 FPS.
Force Vsync with D3DOverrider
- Download and run D3DOverrider
- Click the "+" sign, and locate \Steam\steamapps\common\sonic generations\SonicGenerations.exe
- Open the game's configuration tool and disable vSync. In D3DOverrider, make sure vSync and Triple buffering are on.
- NOTE: You need to keep D3DOverrider running on background.
Set the FPS with FPS Limiter
- For this you need to have your java software updated. Click on the following link, download and install java, and then proceed to the next step. Link: http://java.com/en/download/index.jsp
- Download FPS Limiter.
- Now, on the extracted files in the folder FPS_Limiter_2.0, open up the file "FPS_Limiter_GUI" with "Java Platform". A small blueish window should appear.
- Now, in this window, click on "Search Executable" and find \Steam\steamapps\common\sonic generations\SonicGenerations.exe
- On "Maximum FPS", write down 15, 20, or 30 (select the one most suitable to your system). NOTE: Even if you want 30, you have to re write "30" in the input box, or the final bat file won't be created.
- Click on "create bat". A File Called "SonicGenerations.exe.limited" file should appear in the "FPS_Limiter_0.2" folder.
- Open up the new created file "SonicGenerations.exe.limited". The game should start with your desired frame rate.
Some notes about this:
- The game must be always opened from the bat file created. Also, if you move the FPS_Limiter folder, you must re-create the bat file again.
- Compatible with the D3DOverrider tweak. If you find it not stable enough, use vSync option in the game's configuration tool instead.
- The game won't run at real time at anything bellow 15 FPS. Only use settings that are divisions of 60.
- Once again, make sure that you select your resolution in the configuration tool with 60 Hz.
Issues with Nvidia Optimus laptops
- Open up Nvidia Control Panel.
- Click on "Manage 3D Settings" in the left side of the panel, and click "add".
- Select SonicGenerations.exe with the explorer window [Located at <steam install path> Steam\steamapps\common\sonic generations\SonicGenerations.exe].
- Select the option to force it to use Nvidia Graphics Card.
- Now, go to your desktop. Right click on it, and select "Screen Resolution". Press Detect in this new Window. (If you can see two displays that are grayed out and named after your video cards, you're probably good to go.)
- Choose your Nvidia card and select "Attempt to connect anyway on [VGA/HDMI]". When you found it, click apply.
- Choose extended desktop and apply again. This will force-activate your discrete GPU.
- Open the Sonic Config tool and see if your Nvidia card is present (it really should be), and of course, choose it. Now start Sonic, and it will probably work.
Configuration Tool does not open/crashes
- Download and Install Microsoft Net Framework 4.0 from this link: http://www.microsoft.com/download/en....aspx?id=17851
- NOTE: If the above doesn't, please run Windows Update and install ALL Updates available. This way you can make sure it's not a "flaw" in your system that's causing the problem.
Black screen but can hear sound
- Go to Catalyst Control Center / Nvidia Control Panel and disable all custom Anti Aliasing profiles (reset it to default if needed).
Crash on startup
- Go to Realtek Control Panel (or Sound proprieties on Control Panel for other cards), on "Default Format" make sure you have selected 24 Bits, 48000Hz and not other setting.
- Try running Sonic Generations and Steam as administrator.
- Have Steam verify the integrity of the game cache
- If you still have a crash after doing the above, update your graphic card drivers, download the newest Direct X and install it, and finally run Windows Update and install all updates available.