Minimize GC memory footprint

[frame via Digitalmars-d-learn]

Is there a way to force the GC to re-use memory in already 
existing pools?

I set maxPoolSize:1 to gain pools that can be quicker released 
after there no longer in use. This already reduces memory usage 
to 1:3. Sadly the application creates multiple pools that are not 
necessary in my POV - just fragmented temporary slice data like 
from format(). What can I do to optimize?