Is Thursday 8pm to midnight GMT a particularly busy time for the servers?

[aeristoka]

Do the Module Check and World Size Check.

That all smacks of Module problems first off.

World Size Check

Introduction Foundry VTT worlds can be oversized in two ways: They take up too much data storage, resulting in users hitting their data storage limits. They have too many actors, items, journals, and/or scenes, resulting in the world bloating beyond a size capable of running or being able to be loaded into easily. Both are correlated with one another, but the latter is usually far more of an issue. A world doesn’t have to be completely non-functional to have a size issue- worlds that are star…

Trouble with Modules

Introduction More often than not, if Foundry VTT (on The Forge, or elsewhere) is running slowly, it is usually the fault of module issues (whether a module issue by itself, a module conflicting with another, etc.). This article is intended to give you the tools to find issues with the modules you use so that you can go about running your games, and not worry about fighting the software. Performing a Module Audit First, confirm that there is a module issue by enabling safe configuration for t…

Something else to check (AFTER those two), is the GPU being used by various users’ browsers: WebGL Report

Specifically look at the “Unmasked Renderer”

If it’s Intel UHD, know that FoundryVTT 0.8.x is REALLY hard on those, you’ll have to turn off graphics settings, and turn down FPS to stabilize (if that’s it).