What's your issue with this? Inactive *and* free memory are both available to the Mac, so it will use these 880 MB.

Inactive memory is a bit like a memory cache. If the VM needs a previously released chunk of memory, the contents of that memory are quickly available and nothing will have to be loaded from disk. If another app needs that memory, it just uses it.

As far as I'm aware there are no performance differences involved when using inactive vs. free memory.