Applied in changeset commit:tigase-server|6201aaf9.

Have you tested it to see how much improvements did we get from this?

Not that much - from roughly 3 minutes test (with interval of 1s - roughly 180 items and only MUC and PubSub - metrics are bumped significantly as each component has a lot of default statistics) the memory usage dropped roughly 10MB; I expect that the drop will be more significant for installations with enabled history for a longer period - by default we enable it for 6h (2200 items), so in such case we could save roughly 100-150MB. On bigger installations this may not be much, but sometimes when folks were testing Tigase they were running out of memory, especially with more components enabled.

Completely separate thing is the size of statistics itself, but that wasn't clue of this ticket.