[WIP] Performance improvements

Perf improvement branch for addons loading in apiculture, started ~25% slower than master at running `load_module_graph` when installing `account` (~520s to ~420s on my machine). Down to ~5% (450s).

Not done yet, a big pain point looks to be `_load_data(kind='data')` with an average 2s/call in master and 5s in apiculture.