Howdy Dennis,
I would love to help you with this.
Thank you for reaching out about a suspected bug. This is not a known issue.
There were not a lot of changes between 4.4.2 and 4.4.3. I just manually went through each of them, including the ones in Events Calendar Pro and I am not seeing a single thing that would impact performance.
Typically performance issues will ebb and flow. Based on what I am seeing I’d suspect that downgrade actually had no impact, it was just a coincidence that the issues went away at the same time.
One thing you might do is enable the Month View Cache in WP-Admin > Events > Settings > Display. That should help ease your server’s burden a bit during traffic spikes.
Aside from that my review of your site has not turned up any available performance optimizations. I’m guessing you have around 15 thousand posts based on your event IDs. And it looks like your server is limited to 128MB of RAM. It’s possible that you have simply outgrown your server, but without knowing more all I can do is speculate.
Does that answer your question? Do you have any more questions related to this? I’d love to help as best I can.
Cheers!
– Brook