Hello @cyberbeat - thanks for the report. do you also experience this problem on demo.piwik.org or is it working well there?

On demo.piwik.org there are only 23 cities. I have hundreds of cities alone for germany. So this is not comparable.

I would create own sql tables for this, piwik would be much faster:

type (user_city, user_region, ..), id (city-id/region-id/..), year, month, day, visits,..

and it could even be aggregated with day=0 / month = 0
Very fast with good indices. And if it is even possible to use integer-ids for each entity (city/..) it needs very low storage size.

As for now, for piwik to lookup a monthly history for a city, it has to read many blobs "UserCountry_city", loop all hundrets of city-entries of the array in each blob, find the right city, and do the same for the next blob.

Seems to work well on the demo on monthly data where we have about 2000 unique cities. See for example: http://demo.piwik.org/index.php?module=CoreHome&action=index&idSite=7&period=day&date=yesterday&updated=2#?idSite=7&period=week&date=2017-02-18&category=General_Visitors&subcategory=UserCountry_SubmenuLocations&popover=RowAction$3ARowEvolution$3AUserCountry.getCity$3A$257B$257D$3A$40Vienna$252C$2520Wien$252C$2520Austria

Loads in 5-6 seconds. likely we can't make this much better at this stage

This took around 20 seconds for me each for two tries with different cities (period=day):

http://demo.piwik.org/index.php?module=CoreHome&action=index&idSite=7&period=day&date=yesterday&updated=2#?idSite=7&period=month&date=2017-02-18&category=General_Visitors&subcategory=UserCountry_SubmenuLocations&popover=

And you may have not a low budget vserver like me, and default-php-timeoutlimits will apply a few seconds later. I have switched to another solution in the meantime because of this.

It's true that now it also takes 15-20s here. I'll reopen then