PC optimization

To reduce desyncs, frame drops, and stuttering:

General advice

• Having a powerful PC with expensive CPU and GPU will not automatically let you run these games better. In fact, it can actually run worse - read below on how to set things up to avoid issues.
• On the contrary; it is no longer recommended that you buy used office computers (Optiplex) for this purpose. Newer games run on low-spec "gaming" PCs, so you'll want a standard form factor PC with upgradable parts.
• These are not games you downloaded from Steam that runs better with tweaks to graphics settings, these are arcade games designed to run on specific PC configuration with extremely specific settings. Throw out conventional wisdom on "how to make PC games run better"; instead, the goal is to mimic an arcade PCB as closely as possible.
• For official cab PC specs, see this page.

Caution

If your PC is severely underpowered, even if you follow all the steps here, you're not going to have a great experience.

Similarly, if your sound card / DAC can't properly support the required frequency, bitrate, and output format (wasapi exclusive or ASIO), no matter what you do, you're going to have desync issues.

Monitor checks and framerate

• Press F12 to see the FPS counter, confirm that it's what you expect. Also check your monitor (if not, check log.txt) to see that the game launched at the correct refresh rate. You want those numbers to match (60FPS and 60Hz, 120FPS and 120Hz).
  • Avoid using patches that run at refresh rates not originally intended by the game engine, as it may result in graphical glitches or overlapping sound effects.
  • In menus, your framerate will swing wildly, and this is perfectly normal, as the games aren't perfectly optimized for menus. Check for FPS only during gameplay.
• Do not, under any circumstances, use "skip monitor check" or "shorten monitor check" patches. You might be asking, "why does the hex edit exist if you're not supposed to use it?" - the answer it that those were added for tools and EA server developers to boot the games quicker. If you're actually playing the game, you should keep monitor check.
• It's OK if monitor checks aren't exactly 60.000Hz or 120.000Hz - because they're not like that at the arcade either. For example, IIDX LM cabs stabilize around 119.98xx.
  • Your monitor may boot into 59.94Hz or 119.2Hz (for example). This is OK for most games, as monitor check will eventually stabilize to match your refresh rate.

Multiple monitors

• For IIDX TDJ and SDVX UFC modes, if the main screen locks to the wrong framerate (usually something like 75FPS or 90FPS) instead of 120, it may be caused by the GPU driver being unable to render the primary screen at 120Hz and subscreen 60Hz at the same time.
  • For NVIDIA GPU, ensure that V-Sync options are set to Use the 3D application setting. This usually resolves the issue.
  • For AMD GPU, there isn't a setting for this, and many report problems with subscreen. (Wait for Vertical Refresh option does not affect DirectX games)
  • As a workaround, try launching with Only use one monitor (-graphics-force-single-adapter) and see if it fixes your FPS issues. Alternatively, disable your monitors except the primary.
• Do be careful when using Only use one monitor (-graphics-force-single-adapter) option to display the game full screen on the primary monitor and showing the desktop on the other monitor. For IIDX TDJ, this may result in unstable monitor check, and rare microstutters / desyncs in the game. This may be affecting SDVX VM as well, but difficult to tell. This is most likely due to how DirectX renders full screen games with V-Sync enabled, in addition to drawing the desktop on a different monitor.

CPU

• Set Windows power profile to High Performance to keep the processor frequencies high.
  • Arcade cabinets run with similar configurations where CPUs are held at maximum frequency; some of these games depend on this aspect to keep a steady framerate. IIDX, SDVX, and Nostalgia are known to be heavily affected by this.
  • Make sure you turn it back to normal profile when done playing.
  • Instead of setting an entire profile, you could also edit an existing profile and change Minimum processor state and Maximum processor state to 100%. Be aware that depending on your PC, your CPUs may hit a thermal or current limit by doing this.
• If you have a hybrid processor (E-Cores + P-Cores configuration, such as Intel 11th gen, 12th gen, and so on) - use Process Efficiency Class (-processefficiency) to run the games on the P-cores.
  • You can also use a custom affinity mask with Process Affinity (-processaffinity). You can use this tool to calculate the mask if you are unsure what to do.
• Process Priority (-processpriority) can help but it's recommended that you just leave it to the default, which sets it to high priority.

Turning off CPU idle states (micro-optimizations)

These won't help with stuttering, but may help with keeping a steady framerate, keeping the frame time (milliseconds between frames) in 0-1ms error range. This may help if you have inconsistent timing in IIDX, for example.

• You can go into the BIOS and disable any processor power management features. This would range from: Intel SpeedStep, Turbo Boost, various C-state and P-state scaling, OS-managed processor power management, any processor-idle power save features, etc.
• Disabling HyperThreading/SMT. Not enough data has been gathered but some claim that this may help on some older processors. The typical recommendation is to disable via the BIOS.

GPU

• For NVIDIA GPU, use Add NVIDIA application profile (-nvprofile) option.
  • This will attempt to automatically disable G-SYNC and set power mode to maximum performance.
  • You can also manually turn off G-Sync and set power mode to maximum performance in NVIDIA settings.
  • This is especially helpful for high-end GPUs, because they will downclock aggressively for not-so-demanding games (like the games supported by spice) to reduce heat / power.
• For other GPUs:
  • Make sure VRR (FreeSync, Adaptive Sync) is disabled
  • See if it's possible to set power policy to maximum performance (and not power saving or recommended).
• Always keep V-Sync options to the default (usually Application controlled). This will allow games to enable V-Sync when necessary, which is most games. Never forcibly turn on or turn off V-Sync via GPU settings, no matter what guide you have read has claimed.
  • For example, if you force V-Sync on, for TDJ and VM, both screens will launch at 60Hz, which is not what you want.
• Do not put an artificial FPS cap. Use V-Sync instead.
• DirectX 9on12 options may result in better or worse performance. This is entirely up to your GPU and the game you are trying to run. Generally, try leaving it off first (use DX9), and only if you have issues, switch to DX9on12.
• Forcing triple buffering (using -vsyncbuffer) may reduce stuttering at the cost of latency (Issue 259)

Audio

• Prefer to use exclusive WASAPI or ASIO, and avoid shared mode WASAPI whenever possible. See this page for more details.
• For games with shared audio (DirectSound or WASAPI Shared Mode) - try Low Latency Shared Audio option to reduce latency. See here for more details.
• Don't run audio over HDMI or DisplayPort as they may add significant latency and/or be the source of desyncs.
• Using optical out (SPDIF) port from audio cards usually results in higher latency than analog output.
• Try using Windows inbox audio driver - especially if you have a Realtek audio device, since their drivers can introduce higher latency. The typical minimum latency for Realtek's driver is 10ms, but Windows inbox driver can reach <3ms.
  • You may lose some features with this, however; e.g., Stereo Mix, multiple audio channel support, audio effects and filters, etc.
• Try to disable audio effects in Windows audio settings, which may help with latency.

Memory and disk

• Make sure you have enough RAM. 4gb isn't going to cut it these days, even on a minimal OS setup.
• Ensure XMP is enabled, if your hardware is capable. This helps with frame drops in animation-heavy scenes (Live2D in SDVX for example).
• Consider disabling paging in Windows. Arcade machines run with paging disabled, and the games will assume this is the case (instead of pinning the memory to RAM, they assume that memory is never paged out). While this is not recommended for general use PCs, it is recommended for playing these games to reduce stutters. Just make sure you have enough RAM.
• Most modern versions will require that you run the games off an SSD.
• If log.txt tends to be spammed with messages, it can affect performance; set Log Level (-loglevel) to Fatal if this becomes an issue.
  • Remember to set it back to the default if you want to share log.txt with others for troubleshooting.

Windows

• Disable the hypervisor and VBS (Virtualization-Based Security).
• If you're looking for a good clean OS image - the same used on arcade cabinets - Windows 10 IoT Enterprise LTSC is recommended. Just be mindful, it's not Windows 10 IoT, it's not Windows 10 Enterprise, it's Windows 10 IoT Enterprise LTSC.
  • Contrary to popular belief, IoT Enterprise is a general-purpose OS with a full desktop environment, and is not too different from full version of Windows. (the non-Enterprise IoT SKU is different, however, as it lacks the desktop UI by default).
• Also see Background services section below.
• Disable full screen optimizations - right click on spice.exe / spice64.exe, Properties, Compatibility tab, Change settings for all users, and check Disable fullscreen optimizations. You have to do this for every instance of spice executable (every place where your game is installed), not just once.

On gaming laptops...

Caution

For best experience, it is generally discouraged that you run these games on laptops due to endless oddities people have encountered in the past.

The issues range from: display panel not supporting the required resolution + refresh rate, firmware triggering a thermal throttle resulting in low performance, audio incompatibility issues, switchable graphics causing games to display a white screen....

This does not mean games will run poorly; rather, if the games run poorly, you are on your own to figure out workarounds.

If you have no choice but to run on a laptop:

• Make sure it's plugged into a power source.
  • For thermal and battery issues, many laptop firmware implementations will force the entire system to be throttled on battery power.
• If you have switchable graphics (iGPU + dGPU), make sure it's set to use the dGPU for spice.
  • Do note that in some rare cases, even if you instruct the system to force usage of dGPU for spice, the laptop firmware ignores your preference and use the iGPU anyway; this usually happens when you hit the thermal limit, or when on battery power.
• Try to run on an external monitor.
  • Display built into laptops tend to be more restrictive about what resolution and refresh rate combinations are supported, so connecting to an external monitor alleviates that.
  • Just make sure the right GPU is being used. Some laptops have weird restrictions on which GPU gets used for each HDMI/DisplayPort.

Background services

If you are failing to keep a steady framerate, check for background services, especially ones that inhibit bursts of CPU usage.

Common offenders

• Various Windows background services
  • When stutters occur make a note of the time and check Windows Event Viewer (System and Application channels) for events at that time.
  • Look for things like:
    • Windows Update (set quiet hours or temporarily turn on Do Not Disturb)
    • License check events (Security-SPP)
• Windows Defender (add directory exceptions to avoid scanning game data)
• Various file-sharing software like OneDrive, Google Drive, DropBox
• In-game overlay: Discord, NVIDIA, Xbox GameDVR / Game Bar, etc
• RivaTuner Statistics Server (RTSS), MSI Afterburner - occasionally known to cause mystery crashes as well

Uncommon offenders

• OBS - usually doesn't affect game performance, but may cause spicecfg to launch very slowly
• Other games that install kernel-level anti-cheat
• Razer Synapse (though Razer claims it's fixed in recent versions). Can also cause issues with audio.
• Oculus app / Meta Quest Link (including the background services that cannot be disabled except to uninstall)

Game-specific

IIDX

• If you have an underpowered PC & experience stutters while playing, you could try disabling the video.
  • You can accomplish this by going to the blue menu in song select and changing Camera Display Position to show the camera instead of the BGAs. If you don't have a camera, it'll just show a black box, saving you from a lot of CPU cycles.
  • You may also be able to find patches (hex edits) that disable video entirely.
• For iidx24 and below, try hypersonik.
• For iidx27-29, LDJ patched to run at 120Hz tends to use less resources than TDJ. iidx30 is a mix of both, depending on DLL type. For iidx31+, not a huge difference between LDJ and TDJ.
• If you get bad monitor check or unsteady framerate after enabling Cam Hook feature, turn down the camera resolution and framerate. See the wiki page for more details.

Gitadora

• Gitadora tends to stutter and not scroll the notes smoothly when Full Screen Optimizations is enabled. Right click on spice64.exe, Properties, Compatibility tab, Change settings for all users, and check Disable fullscreen optimizations.

SDVX

• Frame drops from Live2D:
  • Live2D workload is almost entirely CPU bound; make sure you have a good enough CPU.
  • It's often solved by turning on XMP in BIOS, if it isn't on already.
  • Turning off VBS helps a lot as well, just make sure it's actually disabled and not just setting some registry keys someone on reddit told you to do. (open Task Manager and look for Secure System)
• There are some EA server-side flags that can be toggled that may affect client-side graphics performance (SUBMONITOR_VSYNC_ENABLE and USE_CUDA_VIDEO_PRESENTER). See SDVX known issues page.
• If you're using shared mode WASAPI patch, strongly recommended that you try Low Latency Shared Audio option.
• If the game locks at the wrong FPS even though you have done everything correct - for example, games launching at 120Hz but the framerate (on the attract screen) is something like 45-50 FPS no matter what you do - try restarting Windows. Sometimes this fixes it. Seems to affect Windows 11 users a lot.

Nostalgia

• Strongly recommended that you try Low Latency Shared Audio option for lower audio latency.

pop'n music

• Strongly recommended that you try Low Latency Shared Audio option for lower audio latency.
• Try popnhax, which has various options for adjusting audio/visual offset. Ensure that your server allows this mod.

Further reading / Reference

This page is loosely based on https://iidx.org/infinitas_pc.