Following on from Calendar - Cannot Reproduce Rebuilding sitemap - extremely slow when processing Events this is till very much an issue ...
Take this sitemap log, I upgraded from xF 1.5 to 2.2 (and thus this addon too) two weeks ago on Feb 23rd ....

.... sitemap generation went from ~1min to now between 2 and 4 hours.
You can see that, yesterday, I even changed the sitemap generation cron launch time to be in the wee small hours of the morning, so it's during 'quiet' time and not a busy time of day.
And whilst the sitemap generation is running, it 'pegs' mysql CPU usage ...

If I exclude/untick Event content from sitemap options ( /admin.php?options/groups/sitemap/ ) then it generates in less than 1 min ...

If I tick/enable Event content for the sitemap again, then a cli rebuild of the sitemap shows that it's Events being the issue, this below screenshot taken 40 secs after the rebuild was started ...

An untick/exclude Event content from the sitemap, and it takes approx. 5 secs to complete ....

From the mysql processing pegging CPU, it seems perhaps an index or data issue with the Calendar addon data, either from the upgrade or resulting from the upgrade?
What further information do you require to help narrow this down and resolve it?
Take this sitemap log, I upgraded from xF 1.5 to 2.2 (and thus this addon too) two weeks ago on Feb 23rd ....

.... sitemap generation went from ~1min to now between 2 and 4 hours.
You can see that, yesterday, I even changed the sitemap generation cron launch time to be in the wee small hours of the morning, so it's during 'quiet' time and not a busy time of day.
And whilst the sitemap generation is running, it 'pegs' mysql CPU usage ...

If I exclude/untick Event content from sitemap options ( /admin.php?options/groups/sitemap/ ) then it generates in less than 1 min ...

If I tick/enable Event content for the sitemap again, then a cli rebuild of the sitemap shows that it's Events being the issue, this below screenshot taken 40 secs after the rebuild was started ...

An untick/exclude Event content from the sitemap, and it takes approx. 5 secs to complete ....

From the mysql processing pegging CPU, it seems perhaps an index or data issue with the Calendar addon data, either from the upgrade or resulting from the upgrade?
What further information do you require to help narrow this down and resolve it?