1. Install Math::Geometry::Planar
   
2. Edit Planar.pm and add

   use Memoize;
   memoize('CrossProduct');
   [download]

3. Buy more RAM :)
4. Insert: "next polygon if point's coords are out of polygon's box limits" (2 conditionals)
5. Use the isinside function of Math::Geometry::Planar.

Update: Added the 'point out of the box' line.
Update: I used this solution the last year. Other solution is to use the clipping routines of GPC library (in CPAN also) or use Inline::C.