Cache calls

[diocas]

If we cannot remove the need to stat the shares in the short term, we should at least cache these calls.
These, and maybe others... Please evaluate what calls are done frequently.

[dagl]

We should start optimization process by removing unecessary listings of shares everywhere, then do profiling (available in Pycharm) and see which parts of code take the longest, are being used the most frequent etc. Also, caching stats might be problematic