Charge for page load optionally

[breathx]

Problem to Solve

At the moment, while processing queue (see pallets/gear/fn process_queue) we charge gas for loading programs pages every time, but this may be optimised due to overlay existence

Possible Solution

To optimise with overlay:
Store program ids in ext_manager, which already were executed with current ext_manager instance: this means that pages were already read and/or updated, so the next read from db (overlay) is free.

Notes

No response