Instrument environment for performance evaluation

Environment could provide indicators on:
- allocated space,
- used space,
- resize frequency.

These parameters should help user to determine which configuration is the more adapter to its problem:
- CHUNCKED is adapted to large-scale problem in which huge space is needed and allocating it in one shot is critical
- FLATTEN is adapted to low-memory consumption problem.

Each of them should be accurately configured wrt to the analysis of the parameters

The issue does not name a file, test, or entry point for the Environment instrumentation. First identify the Environment component and how CHUNCKED and FLATTEN are configured, then determine how allocated space, used space, and resize frequency should be measured. Done means these indicators support accurate configuration decisions for both modes.

Written by the indexing model from the issue text.