Thank you for your review and high rating! But seems you have some issues on your site which are not related with JComments. May be this is problems with server's configuration or with caching.
I know sites with JComments where about 500 000 comments. And I have copies of databases of some these sites for tests. Before releasing of new JComments version I make performance tests with these databases. Also I have two old users who uses (and tests all new versions) JComments since 2006. At this moment on the first website we have 35 000 comments (not too much for 7 years) and the second one has 85 000 comments. And they have not any problems with performance.
In my mind 10 000 comments is not such big number of comments to get performance problems. Besides the last JComments version has alot improvements and optimizations and it more lightweight and fast than previous versions.
So if you have got issues with performance - contact me via email (you can find it easily in JComments manifest or code) and I will try to help you.