POE Betrayal Loading Lag

In the Betrayal league content, there are 17 members of the Immortal Syndicate who can appear in areas that you play through. As with all other content in Path of Exile, it's important that the game assets for these enemies are loaded before you encounter them, otherwise your client will have to load them synchronously, which stalls it for a period of time. 

Because multiple Betrayal encounters occur in an area, and the results of one encounter can affect which Syndicate members spawn in the subsequent encounters, it's not possible to know in advance which specific Syndicate members need to be loaded, so we have to preload all of them. 

On most users' machines, this preloading is complete before any Syndicate members are encountered in the area, with no performance impact. However, on slower machines or ones with platter-based hard drives, preloading can take so long that the right enemy isn't loaded before it is encountered. This causes a big stall in the middle of combat, which is unacceptable. 

In a patch in the next week or so, GGG will flag these monsters as being mandatory to load during the load screen of the area, which will prevent any such freezes (but will somewhat increase load times for these areas). 

Later this year, GGG expect to deploy the asset loading optimisations that we are using on consoles which will make platter-based hard drives much faster and will improve loading speed in general.