In the rare event that too much texture data is loaded into VRAM, and the required texture is not present, the GPU will need to request it from RAM and overwrite one or more existing textures to make room for it. This is likely to worsen over time as the memory becomes fragmented, and it introduces a risk that the texture just flushed from VRAM needs to be pulled again within the same frame. This will result in a serious case of memory thrashing and should be avoided at all costs.

This is less of a concern on modern consoles such as the PS4, Xbox One, and Wii U since they share a common memory space for both CPU and GPU. This design is a hardware-level optimization, given the fact that the device is always running a single application, and almost always rendering 3D graphics. However, most other platforms must share time and space with multiple applications, where a GPU is merely an optional device and is not always present. They, therefore, feature separate memory spaces for the CPU and GPU, and we must ensure that the total texture usage at any given moment remains below the available VRAM of the target hardware.

Note that this thrashing is not precisely the same as hard disk thrashing, where memory is copied back and forth between the main memory and the virtual memory (the swap file), but it is analogous. In either case, data is being unnecessarily copied back and forth between two regions of memory because too much data is being requested in too short a time period for the smaller of the two memory regions to hold it all.

Avoiding this behavior may require customizing texture quality and file sizes on a per-platform and per-device basis. Be warned that some players are likely to notice these inconsistencies if we're dealing with hardware from the same console or desktop GPU generation. As many of us will know, even small differences in hardware can lead to a lot of apples-versus-oranges comparisons, but hardcore gamers tend to expect a similar level of quality across the board.