removing zone triggers reading all signconfs

Today, I removed a zone, changed something one another one, and asked for
the other one to be resigned, I was waiting for the changes to propagate,
and as it was not happening fast enough for me, I went to have a look,
and...
It seems that removing a zone forces the signer to reread all the zones
configurations. It seems quite a strange idea to do that to begin with, but
now, with the number of zones I have (>1500) it takes ages, (a bit like
the signer takes ages to launch,) so, I wonder, would it be possible to not
do that as I don't really see the point for it. I don't know how the signer
works internally, and how it stores the zones configuration, but there
should be an easier when than rescanning all of them when you only want to
remove one.