That's almost the canonical example. Say for a particle system you use a fixed-block allocator that's the size of your particles. Now your allocations are quick

That's almost the canonical example. Say for a particle system you use a fixed-block allocator that's the size of your particles. Now your allocations are quick since you don't have to do fitting and you don't fragment memory since they're all clumped together. Other common trick in video games is to have a single-frame arena allocator for objects that are transient frame to frame. You just move a pointer forward and reset the pointer at the end of the frame.