Incremental garbage collection ?

[binni@...]

Hope you can help me with this guys,

We are planning on using lua for equipment control and for that purpose out
PLC engine has been modified so that it can call lua subroutines.
This works well and seems to be fast enough for our needs and makes a lot
of our controls much simpler, both to write and to maintain (compared to
PLC code)
What happens is that periodically the PLC scan time jumps from 2-3
milliseconds to 32 milliseconds which is unacceptable for us.  We believe
that it
is the garbage collection that is kicking in and taking up all this time.
Is this something that we have to try to live with or is it possible to do
some sort
of incremental garbage collection through a low priority taks that does
nothing but do garbage collection.  Is the time it takes to do garbage
collection "fixed"
or would it help to do garbege collection more frequently ?

-Binni