Working with CPU-intensive particle systems can stress even the most robust of computers, so Particle Flow includes a Cache operator that lets you store the results of computation for faster playback during development. This operator provides basic functionality, which is extended significantly by two additional Cache operators included with Box#3 Pro.
The Cache Disk operator works much like the original Cache operator, except that it lets you store the cache on the hard disk, separate from the main 3ds Max scene file. The entire cache doesn't need to fit into a single, bloated file because each frame's data is stored in a separate file. This results in faster response: When you jump to a particular frame, Particle Flow needs to pull only a single relevant file from the hard drive. Also, you can rearrange the animation or shift it in time by modifying the file indices.
As with the original Cache operator, Cache Disk lets you pre-calculate and store all the activity in a particle system so that you can play or scrub the animation quickly without having to wait for calculations. The main benefit is that the only limit on the size of the cache is the amount of free space on the hard drive, rather than system RAM as in the original Cache operator.
Box#3 Pro also includes a Cache Selective operator that lets you exclude certain types of data from the cache. As with the Cache Disk operator, you can specify post-cache operators. You define the most calculation-intensive properties of a particle system (usually the motion), pre-calculate it once, and then work with other particle system properties via post-cache operators (shape, size, orientation, mapping, color etc.).