There's a prevelant talk that high poly items causes pink flashing, and missing body or hair in thumbnail.

I think the latter is true, however, I'm not sure about the first.

I could guess that the filesize is affected, maybe there would be more lag.

Anyone have a clue with that happens?

CAS items at roughly 25-30.000 polys and over causes invisible items in the loading screens, and also need shaders enabled to display properly on lots (possibly also CAS, can't remember).

It can potentially cause lag, but it's not so much that one item, it's more when it all adds up. One hair or object won't make that much of a difference, but 8 hairs, 8 outfits and a house filled with 200 high-poly objects can quickly cause some trouble, especially paired with large textures.

Textures can often be worse for pink-flashing. Especially if they're larger than 1024x1024 or if they're set as RAW textures in the file instead of DXT (bigger filesize), but also if there are multiple textures.

Repo'd items (items that borrow textures from other items) can potentially help, reducing the texture size wherever possible (especially for objects that don't need a large size), removing unnecessary textures, removing unnecessary TXMT effects if shaders are used, and so on.

Using shaders is also one of the main causes of pink-flashing troubles.

Shadows and reflections can also cause some lag, as can most of the settings in the Graphic settings if turned on high, though some should be prioritized over others if need be, especially if using CC. How much lag depends on the computer system - most fairly decent computers should be able to handle it.

The main thing about high-poly items (in my opinion) is that most of them rarely have any need to be higher than 30k when they are for a game, no matter the detail. Most hairs and clothes, if made properly, are going to look just fine with much less. Same with objects. There are so many examples of items that look very good and are in the 100-5000 poly area. You can get very far with a smaller well-made texture and a well-made lower poly mesh (and UVmap).