[dgrnbrg]

It seems like a solution to getting more performant, lower overhead GC would be to allocate GC pools that contain only a specific kind of object, and then generate specialized code to mark/sweep those pools (since you could elide the object headers, since everything in the pool is the same time. These pools could be mananged by a GC-pool GC, so that as new object types were created and destroyed, their pools would get allocated and garbage-collected.

Are there any systems that currently do this?

[pcwalton]

Yes, modern garbage collectors usually allocate objects into bins, which don't have headers since the objects are of fixed size.