Foundry Performance Tuning & Troubleshooting

General Thoughts
Foundry VTT can use a lot of resources. On shared hosting, the best results come from keeping your setup lean and realistic.

The short version: more players, more modules, and bigger assets all increase load. If your world is large or heavily modded, a higher plan may be necessary.

Keep these rules in mind:
  • Your game is limited by the slowest player. Weak hardware or a poor connection on one player's side can affect everyone.
  • Foundry needs a stable connection. If someone has packet loss or unstable internet, disconnects and lag are expected.
  • More modules = more load. If performance is bad, reduce modules first.
  • Large images, audio, and video files slow everything down. Optimize assets before uploading them.

If performance suddenly drops, simplify the world first, then test again.
Troubleshooting Steps
Start with the basics. Most performance problems come from modules, browsers, or oversized worlds.

  • Start in Safe Mode. This disables modules and tells you quickly if one of them is the problem.
  • Open your browser console and clear out errors and warnings. If the console is noisy, something is wrong.
  • Test a blank world with the same game system and no modules.
  • Try another browser and clear cache before testing.
  • Disable browser extensions that may interfere with Foundry.
  • Reboot your computer and/or internet router.
  • Clear chat logs and fog of war regularly.
  • Lower FPS to 30 or less.
  • Use "Fix My Server" if the server will not start correctly.
  • Turn off mouse pointer tracking if you do not need it.
If the issue still happens after these steps, send support the exact error and what you already tested.
Linking to External Assets
Local assets are served directly by your game server. External assets are served somewhere else.

That means:
  • Local assets: use your server resources and bandwidth.
  • External assets: do not use your server bandwidth, but they are only as fast as the outside host serving them.
A common issue happens after a migration. If your world still points to files on an old host, those files become external assets and may load slowly or fail completely.

File Size Considerations
Big files are one of the fastest ways to make a world feel slow.

Use these formats when possible:
  • Images: WebP
  • Audio: MP3 or OGG
  • Animations/Video: WebM
Keep quality reasonable, but prioritize smaller files. Optimized assets load faster and cause fewer problems for players.

Compendiums vs World Content
A compendium is long-term storage. Your world tabs are active working content.

The important difference:
  • Compendium: good for storing actors, items, and journal content you are not actively using.
  • World content: anything imported into the world adds to the active load.
If you import too much from compendiums into the world, memory usage goes up and performance gets worse. In extreme cases, this can contribute to out-of-memory crashes.

Best practice: keep content in compendiums until you actually need it, and only import what the game is actively using.