Thank you very much for your feedback! I’m really sorry for the issue. With the current version there can be speed issues if there are a LOT of calendars, like more than 50. For the moment we can only suggest to reorganize the structure of the data, perhaps merge several calendars into one.
Hello,
in version 4.6.60 we’ve implemented a few optimization changes that reduced the number of database queries, I hope it’ll help.