Arnaud Lesauvage <thewild(at)freesurf(dot)fr> writes:
> I was advised the PostGis list to use a multicolumn index on both
> the integer column and the geometry column.
You could try that (put the geometry column first!). I'm not sure how
effective additional columns in a gist index really are, but it's worth
experimenting with.
regards, tom lane