The raw data for a 10^7 x 10^2 array takes up 1_000_000_000 bytes of data per byte of the data type. For most data types, that's more than a 32-bit machine can handle, regardless of whether C, PDL or Perl. That's why a sparse matrix was requested.

PDL could very well have such a data structure, but it's not "well optimized C libraries" that are going to make the difference.