updated with new version 1.3.2 which is the first release-candidate - which means close to "not beta anymore".
i hopefully fixed the performance issues completely, seems like it was a mistake on my side. Just test out if it works better for you. In my test and productive environment, the page load time was decreased significantly.
If you still are experiencing delayed loading times beyond 2 seconds, activate the "Debug Profiling" plugin in your Admincp > Plugins list and monitor the debug output at the top of the page. (should work only for the showthread page for now) This should give you an overview on how many times the function has been called and how long it took to process a single request.
FYI: Only administrators can see the output, so have no fear
More features will follow as I get the time to implement them.