Howdy 7iber,
We have worked very hard to make our plugin as performant as possible, while still implementing the huge array of options our users want. Virtually every release we take a scrutinizing look at performance and see if there is anything more we can do.
It sounds like you might simply require a more powerful server. Or, often times web hosts will allow you to increase the memory limit on your current server. Here are some helpful links regarding this:
Keep in mind that WordPress is a powerful application, and our Calendar only adds to that power. Often times the cheapest hosts out there simply will not accommodate these, especially once you start having a lot of posts or events.
There is one other thing to try, that might help things allow. Try pasting this snippet in your theme’s functions.php file. If your server has a low limit set on joins, then this can sometimes fix that bottle neck.
Does that all make sense? Please let me know if you have any more questions, or if the above was able to help you resolve the issue. Thank you very much!
– Brook