memory leak when doing lots of ideal tests

I'm trying to find elliptic curves lying on a quartic surface; there are probably clever ways to do this, but at the moment I am finding lots of quadrics through an integer point on the surface, then iterating over pairs of them and checking

x^4+y^4+z^4-67*t^4 in ideal(f1,f2)

This leaks about 2MB memory per second, presumably because the Groebner bases for the ideals are being cached; is there a way to tell sage not to cache them?