Batocera tuning

Batocera Tuning

Performance: why the frontend or a game runs slow, and how to fix it. Assumes the connection pattern and batocera.conf model from batocera-ops. The theme throughout: diagnose the machine state before blaming config, themes, or gamelists. Most "it got slow" reports are a throttle or a leak, not the thing the user suspects.

Diagnostic order for "the frontend is slow"

Work down this list; each step is one command and rules out a whole class:

1. CPU governor. A frontend that is laggy from cold boot and stays laggy through a reboot is almost always the CPU stuck in powersave:

   SSHB "cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor"
   

   If it says powersave despite system.cpu.governor=performance, see the governor fix below. This is step 1 because it's the most common cause and the cheapest check.
2. ES event hooks. Lag that gets progressively worse as you navigate, and is cured only by an ES restart, points at a slow/leaky ES event hook. ES runs every executable in its scripts dirs on menu events — a system-selected hook fires on every carousel tile change and can add permanent per-frame cost. Audit /userdata/system/scripts/ and /userdata/system/configs/emulationstation/scripts/. Because hooks are global (not theme-scoped), this masquerades as a "theme-independent ES bug" — the tell is that it accumulates per tile visited. See below.
3. Texture cache. Lag that's fine at first and worsens with a large media set, with revisits staying fast, can be ES texture-cache eviction thrash. Raising MaxVRAM in es_settings.cfg (e.g. to 1024) can help, but measure — on some builds the GPU floor and MaxVRAM make no difference and the real cause is #1 or #2.
4. GPU clock floor. Only chase this after 1–3. On a vsync-paced frontend the GPU often won't upclock on its own, but pinning a higher floor frequently makes no measurable difference — A/B it before persisting anything.

Measure, don't assume: a framerate overlay (DrawFramerate=true in es_settings.cfg) plus the batocera-ops screenshot loop lets you read fps on a specific tile remotely. Turn it back off when done.

Do not drive these tests with synthetic input (see batocera-ops doctrine). Ask the human to navigate, and read results from logs / screenshots / /proc. Also note: a governor re-assert (below) may fire ~60–90s after boot, so the first minute can feel slow even when fixed — don't let anyone judge inside that window.

The v43 governor-at-boot failure

On some v43 builds, system.cpu.governor=performance fails to apply at every boot: the init script (/etc/init.d/S18governor) runs but its sysfs write silently fails (redirected to /dev/null), leaving intel_pstate's default powersave (~1.5 GHz vs the chip's ~3.4 GHz). A reboot does not fix it — every boot lands in powersave.

Fix: re-assert the governor from a boot service after userspace is up, and periodically thereafter. In /userdata/system/services/custom_service (the v43 replacement for custom.sh; see batocera-maintenance), add a loop that runs /etc/init.d/S18governor start ~60s after boot and then hourly. Verify across a reboot:

SSHB "cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor"   # after ~90s uptime

Bonus hazard covered by the same hourly re-assert: batocera-shutdown's fake-suspend can save the governor state such that a repeated fake-suspend strands the machine in powersave permanently. The periodic re-assert covers that too.

The overclock / CPU-speed scoping trap

Overclock and CPU-speed core options are keyed on the emulator/core context, which is not always the rom directory you think you're affecting. Example: a fbneo.fbneo-cpu-speed-adjust=200% key applies to launches in the fbneo core context — it does not reach games launched out of a different rom directory (e.g. neogeo) even though they run on the same underlying core. If Neo Geo games still run at 100% after you "set the fbneo overclock," that's why: they need a neogeo.<key> of their own.

To find the right scope, launch the game and read /userdata/system/logs/es_launch_stdout.log for the system/emulator/core it actually used, then key the override on that name. And remember the .opt exception (batocera-ops → batocera-conf): a per-game .opt replaces global core options, so a game with an .opt takes its CPU value from inside the .opt, not from batocera.conf — set it there for that game.

ES event-hook frame cost

Expanding on step 2: an installed ES event hook (say, a home-automation integration that pings a server on system-selected) executes on every carousel move. Even a fast-looking script can leave a couple of milliseconds of permanent per-frame cost that accumulates per tile visited until ES is restarted, dragging a 60 fps menu down to single digits after a while. Diagnosing it:

• Symptom shape: per-visit accumulation (revisiting two tiles 50 times degrades as much as visiting 50 different tiles), cured only by ES restart.
• Confirm with ES debug logging (es.customsargs=--debug in batocera.conf, picked up on a plain kill -9 restart of ES, no reboot needed): you'll see the hook fireEvent → executing: line on every tile change.
• Fix: remove the hook. If you want the integration, poll from the other side instead of installing an ES event hook. Trap: some agents/services rewrite their hooks on every boot/start — remove the service/agent that installs them, not just the hook files, or they reappear next boot.

Tuning 3D-heavy games (PSX, PS2, Dreamcast, N64 class)

Graphics tuning only pays off on 3D systems whose emulators expose rendering levers. 8/16-bit libretro systems render native-res for pennies — they have no resolution or backend knobs worth touching, and "tuning" them means frameskip or the overclock keys above. Don't burn a session tuning a 2D system.

Know the hardware before proposing values. One command each:

SSHB "batocera-info"        # CPU model/cores, RAM, display resolution
SSHB "batocera-vulkan hasVulkan; batocera-vulkan hasDiscrete; batocera-vulkan listDevices"

An iGPU-only box (hasDiscrete false) and a discrete-GPU box want different defaults; find out which you're on before copying settings from a forum post.

The two levers, in order:

1. Internal resolution scale — the dominant cost knob on 3D emulators (duckstation_resolution_scale, pcsx2_resolution, flycast_render_resolution, …). Each step multiplies fill-rate cost; on an iGPU, 1x-2x native is realistic and forum-copied 4x+ is not.
2. Graphics backend — Vulkan vs OpenGL. On Intel iGPUs Vulkan is a common stability problem, not just a performance choice (see the table below).

Discover the exact key names and accepted values per emulator in es_features.cfg (batocera-ops → batocera-conf reference) rather than guessing — values can be opaque enums (PCSX2 OpenGL is ps2.pcsx2_gfxbackend=12).

Crash and slowdown patterns in the emulator logs under /userdata/system/logs/ (read es_launch_stdout.log first to see which emulator/core actually ran):

Log pattern	Likely cause	First fix
VK_ERROR_*, vkQueueSubmit failure, device lost	Vulkan instability, esp. on Intel iGPUs	Switch that emulator's backend to OpenGL
std::bad_alloc, OOM-killer hit in dmesg	Resolution scale / texture cost beyond memory	Drop resolution scale one step
Slowdown or audio crackle, no crash	GPU fill-rate saturated	Drop resolution scale before reaching for frameskip

Scope fixes per game where one heavy title is the problem (psx["Game (USA).chd"].duckstation_gfxbackend=…) rather than degrading the whole system for it.

Run-ahead and input latency

Run-ahead hides emulation input latency by simulating N frames ahead each frame — great feel, but it multiplies CPU cost (each run-ahead frame is a full re-emulate) and needs a core that supports save-states. Enable modestly (<system>.retroarch.run_ahead_frames=1) on systems where the CPU has headroom; back off if it introduces audio crackle or drops frames. On a weak cabinet iGPU, prefer 1 frame and reserve it for the systems where latency matters most (fighters, shmups) rather than globally.