fix data house keeping / cleanup

[nitram509]

motivation

Internal data structures (slices, maps, etc) do grow over time and occupy memory.
Hence, all objects shall be removed, once no more needed.

[rowdyroad]

pls check my commits, if it's workable for you i can make a pull request
rowdyroad@f4d6d2f
rowdyroad@b378418

[nitram509]

@rowdyroad thank you for your proposal.
That would be a great extension and worth a PR, for sure.
I would be happy, if you would create a PR :)