Non-memoizing value instances
Sometimes memoization done in instances just wastes memory. Should we decide whether memoization on value instancesnis necessary based on AST features?

1. simple redirections should always bypass memoization **if no special properties like `_pos` are accessed**?
2. for results of computations it should approximate count of accesses to the prop by count of references to it (including `bypass` ones), multiply it by cost of operation (I guess we can try to use values from [Agner Fog tables](https://www.agner.org/optimize/instruction_tables.pdf) multiplied by the complexity of an operation as an approximation of its cost), divide by amount of space consumed (let's call this value `worthness to memoize`) and compare against some tunable threshold (KSC should have a feature to add a comment of worthness to each `value` instance). If worthness is above the threshold KSC should memoize, otherwise it shouldn't.