cycle-atlas/.agents/skills/after-effects/references/performance-triage.md

Performance Triage — Slow, Laggy, Crashing, Frozen

Diagnose slow previews, slow renders, freezes, and crashes in a fixed order, from cheapest fix to most invasive. Work top-down and stop when the symptom clears — most issues are solved in the first few steps.

Most fixes live in Preferences. Open Edit > Preferences (Windows) or After Effects > Settings/Preferences (macOS).

First: identify the symptom

• Slow / non-real-time previews (RAM preview) → Flow A
• Slow renders (final output) → Flow B
• Crashes / freezes / hangs → Flow C

Flow A — Slow previews (do in order)

1. Set Resolution to Auto/Half/Third. In the Composition viewer, change Resolution from Full to Half or Third. Adaptive/Draft resolution gives the biggest instant win.
2. Enable Multi-Frame Rendering (MFR). Preferences > Memory & Performance > Enable Multi-Frame Rendering. Uses all CPU cores for preview and render (AE 2022+). Confirm "CPUs reserved for other applications" isn't set too high.
3. Check RAM allocation. Preferences > Memory & Performance. Leave ~6 GB for the OS; give the rest to AE. Too little RAM = a tiny green preview bar.
4. Set Fast Previews to Adaptive Resolution. Viewer's lightning-bolt icon → Adaptive Resolution (degrades resolution only while interacting).
5. Purge the cache. Edit > Purge > All Memory & Disk Cache. Stale/full cache stalls previews.
6. Verify the Disk Cache is on a fast drive. Preferences > Media & Disk Cache → Enable Disk Cache, point it at a fast SSD/NVMe, give it 50–100+ GB. Never on a slow external HDD.
7. Solo the offending layer/effect. Toggle effects off (the fx switch) or solo layers to find the bottleneck. Heavy culprits: blurs, glows, Mocha/tracking, particles, expressions, large 3D, and many third-party plugins.
8. Enable GPU / hardware-accelerated decoding. Preferences > Video Preview (Mercury GPU) and Preferences > Import > Hardware Accelerate H.264/HEVC decoding. Helps long-GOP source footage.
9. Pre-render or proxy heavy comps. Pre-render a finished/slow precomp to ProRes and set it as a proxy (File > Create Proxy, or right-click footage → Set Proxy). Frees compute for the part being worked on.
10. Trim the work area to just the section in progress so RAM preview fills faster.

Flow B — Slow renders (do in order)

1. Confirm Multi-Frame Rendering is on (Memory & Performance) — the single largest render speedup on multi-core CPUs.
2. Render with the Render Queue for masters, AME for delivery — and don't run heavy work in AE while AME renders.
3. Enable hardware-accelerated decoding for H.264/HEVC sources (Preferences > Import).
4. Pre-render slow precomps once and reuse them, instead of recomputing every frame. Heavy effect stacks, time-remapping, and 3rd-party renderers benefit most.
5. Replace effects with cheaper equivalents where possible (e.g., Fast Box Blur over Gaussian; native over plugin).
6. Convert long-GOP source to an intermediate (ProRes/DNxHR). Decoding H.264 every frame is slow; ProRes is cheap to read.
7. Check the renderer: Composition > Composition Settings > 3D Renderer. Classic 3D is fastest; Cinema 4D/Ray-traced renderers are far slower.
8. Disk Cache on NVMe so repeated frames aren't recomputed.
9. Close other apps, especially other Adobe apps and browsers, to free RAM/CPU for MFR.

Flow C — Crashes / freezes / hangs (do in order)

1. Purge cache (Edit > Purge > All). A full/corrupt cache causes hangs.
2. Clear the Disk Cache folder in Preferences > Media & Disk Cache > Empty Disk Cache. Corrupt cache files cause crash-on-open.
3. Update GPU drivers (NVIDIA Studio driver / AMD). Outdated/Game-Ready drivers cause Mercury GPU crashes. As a test, switch Project renderer GPU→CPU (File > Project Settings > Video Rendering and Effects: Mercury Software Only).
4. Reset Preferences: hold Ctrl+Alt+Shift (Win) / Cmd+Opt+Shift (Mac) while launching AE. Corrupt prefs are a top crash cause.
5. Disable third-party plugins by temporarily moving them out of the plug-ins folder, then reintroduce to find the offender. Old plugins are a leading crash/freeze source after AE updates.
6. Check Disk Cache and Output drives for free space. A full scratch/cache disk causes freezes mid-render.
7. Lower or disable MFR if crashes appear only during multi-frame render — some plugins are not MFR-safe; reserve more CPUs or disable MFR for those projects.
8. Roll back the AE version if crashes started right after an update. Install a previous version via Creative Cloud (Other Versions) — many crash waves are version-specific regressions.
9. Look for a single corrupt asset — import comps one at a time, or replace footage, to isolate a bad file.

Quick reference

Symptom	First three moves
Choppy RAM preview	Half resolution → enable MFR → purge cache
Tiny green preview bar	Raise RAM allocation → SSD disk cache → trim work area
Slow final render	Enable MFR → HW decode H.264 → pre-render precomps
Crash on launch	Reset prefs (modifier keys) → empty disk cache → update GPU driver
Crash mid-render	Free disk space → disable/reserve CPUs for MFR → disable 3rd-party plugins
Started after update	Roll back AE version → update plugins → reset prefs
Laggy with footage	HW-accelerated decode → transcode to ProRes → proxy heavy comps

Gotchas

• MFR needs RAM per core. With many cores but little RAM, MFR can underperform or stall — aim for several GB per active core.
• Game-Ready drivers crash AE. Prefer the Studio driver branch on NVIDIA.
• Disk Cache on an external HDD is worse than none — it must be SSD/NVMe to help.
• Plugins lag behind AE updates. After a major AE upgrade, a sudden crash wave usually means a plugin needs updating or is not MFR-safe.
• Purging clears the green bar. Previews must rebuild afterward; that initial slowness is expected, not a new problem.
• CPU/GPU effects are not equal. A few GPU-accelerated effects are fast; mixing many CPU-only effects forces round-trips that kill preview speed.
• Don't render in AE and AME simultaneously on the same machine — they fight for cores and RAM.

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AE Performance — Detailed Diagnostics Reference

Preference locations and recommended values

Setting	Path	Recommended
RAM for AE	Preferences > Memory & Performance	Total RAM minus ~6 GB for OS
Multi-Frame Rendering	Memory & Performance > Enable MFR	On; reserve 0–2 CPUs for other apps
Disk Cache	Media & Disk Cache > Enable Disk Cache	On, SSD/NVMe, 50–150 GB
Conformed media cache	Media & Disk Cache	On SSD, separate from project if possible
HW decode (H.264/HEVC)	Import > Hardware Accelerate Decoding	On
Mercury GPU	Project Settings > Video Rendering and Effects	GPU (CPU as crash test)
Fast Previews	Viewer lightning icon	Adaptive Resolution

Multi-Frame Rendering (MFR) tuning

• Introduced in AE 2022 (22.x); renders multiple frames in parallel across CPU cores for both preview and final render.
• RAM is the limiter. Each rendering frame needs memory; with too little RAM, AE quietly reduces the cores it uses. Target several GB of free RAM per logical core you want active.
• "CPUs reserved for other applications" trades render speed for system responsiveness. Set 0–2 on a dedicated machine.
• Some legacy/3rd-party effects are not MFR-safe and can crash or render incorrectly under MFR. If a specific project crashes only with MFR on, disable MFR for that project or update the plugin.

GPU and drivers

• Use the NVIDIA Studio Driver (not Game Ready) for stability with Adobe apps; keep AMD drivers current too.
• Mercury GPU acceleration speeds some effects and the renderer. If AE crashes on launch or while playing back, switch Project Settings > Video Rendering and Effects to Mercury Software Only to confirm GPU/driver fault, then update drivers.
• Hardware-accelerated decoding (separate from rendering) speeds reading H.264/HEVC source footage; enable in Preferences > Import.

Disk cache sizing and placement

• Put the disk cache on the fastest local drive (internal NVMe ideal). Never on a slow USB HDD or a network drive.
• 50–150 GB is typical; more helps long projects retain cached frames between sessions.
• Symptoms of a bad cache: hangs on open, garbage frames, refusal to play. Fix via Empty Disk Cache and Edit > Purge > All.
• Keep the cache drive from filling up — a full cache/scratch disk causes mid-render freezes.

Pre-render and proxy workflow

1. Identify a slow, finished precomp (heavy effects, particles, 3D, tracking).
2. Add it to the Render Queue and render to ProRes 422/422 HQ (or PNG sequence).
3. Right-click the footage/comp in the Project panel → Set Proxy > File, select the rendered file. A box icon shows the proxy is active.
4. Toggle the proxy off for final render if you want to re-render at full quality, or keep it if the pre-render is final.
5. Alternatively File > Create Proxy > Movie/Still to queue a proxy directly.

• Proxies let AE substitute a cheap-to-read file for an expensive comp/footage during editing.

Heavy effect culprits (preview/render cost)

• Gaussian Blur, Camera Lens Blur, Glow → use Fast Box Blur where acceptable.
• Particle systems (Particular, Form), Element 3D, Plexus.
• Mocha tracking, Warp Stabilizer (analysis), motion tracking.
• Expressions that read many layers/time, especially per-frame heavy ones.
• Nested precomps with collapsed transformations and continuous rasterization.
• Ray-traced / Cinema 4D 3D renderer vs Classic 3D.

Version-specific culprits

• After a major AE update, a sudden crash/slowdown wave usually traces to a third-party plugin not yet updated for that AE version — update plugins or remove them to test.
• If problems began immediately after updating AE, install the previous version from Creative Cloud → app → Other Versions, and report the regression.
• Reset corrupt preferences by holding Ctrl+Alt+Shift (Win) / Cmd+Opt+Shift (Mac) during launch; this resolves many post-update oddities.

Isolation checklist for crashes

1. Reset preferences (modifier-key launch).
2. Empty disk cache + Purge All.
3. Update GPU driver (Studio branch).
4. Move 3rd-party plugins out, relaunch, reintroduce one at a time.
5. Switch Mercury to Software Only to rule out GPU.
6. Import comps/footage incrementally to find a corrupt asset.
7. Disable MFR for the project if crashes are MFR-specific.
8. Roll back AE version if the crash wave is version-correlated.

When to pre-compose vs pre-render

• Pre-compose to organize and to apply an effect to a group — does not by itself speed anything up (it can even add overhead).
• Pre-render (render to a file + use as proxy/footage) when a precomp is finished and slow — this is the actual performance win.