Direct answer
Server resource packs mainly affect client download and rendering rather than server tick calculations. Heavy textures or models can reduce client FPS while large downloads slow login.
How to check it
- Ask affected players whether the issue is low FPS, a slow resource-pack download or delayed joining.
- Measure the pack ZIP size and confirm that its hosting URL actually serves the file efficiently.
- Compare client FPS with and without the pack using the same view distance and location.
- Check server tick time separately with spark; do not assume the pack causes high MSPT.
What to change
- Compress/resize unnecessary high-resolution textures and reduce excessive animated textures or model complexity where appropriate.
- Host the file on a reliable public endpoint instead of making the Minecraft process proxy a large download unless intended.
- Recalculate the SHA-1 whenever the ZIP changes and verify it still matches the server configuration.
Software and version notes
A client with a weak GPU may struggle with a pack even when the Java server is healthy. A server plugin that dynamically updates packs may introduce extra workload, but this must be measured separately.
Practical example: Example: users reporting “lag” only after accepting a high-resolution pack might have low client FPS, while server TPS stays steady. Reducing texture resolution could improve their client, but will not fix a plugin performing expensive synchronous world work. Keep those two investigations separate.
Verify the result
- Check affected clients’ download success and FPS.
- Ensure the pack still renders all required assets and that the hash changes with the file.