Now, I have not not aware of anyone else experiencing this issue. Connections actually scales extremely well. Many use it with 100/s to 1,000/s and even hundreds of thousands of entries.
The only two items that I feel could cause spikes is if you are trying to show a lot of entries on a single page. This would not be a Connections issues. The same would happen if you tried to loads equal number of WP posts on a single page. The other is the Face Detect extension can be very CPU intensive.
Does that help?