So it doesn't look like IO matters much.

But better get rid of the source filter.

If you really want factor 4 you'll have to try to reactivate one of the pre compile projects like perlcc or find another way to start an image of the executable.

I've also looked for a suspend mode but that's not rpi's philosophy. It's supposed to he running constantly. Your requirement is not normal.

Anyway as long a you don't profile your project we gonna be shooting in the dark.

So sorry I'm out now.