I've blogged a few times on Sametime's Web Connect API and how it might ease STLinks integration woes. Specifics including code, performance, and architectural advances can be found in The UC View's article Teach IBM WebSphere Portal to do new IBM Lotus Sametime tricks with the Connect Web API toolkit.
STLinks areas of improvement can be found in the following excerpt from the article:
"Performance. Because the STLinks API is built on an applet-based foundation, there are immediate performance concerns. Consider that each time you visit a page inside IBM WebSphere Portal, the STLinks applet loads. Every time you exit a page to open another page, the applet must destroy itself. However, there is a configurable interval during which the applet wakes and sleeps before it destroys itself. This improves performance but still does not enhance it enough. All of this results in a constant loading and unloading of the STLinks applet when users browse IBM WebSphere Portal content, with the net effect of a noticeable difference in page load time.
Java version behaviors. Because the STLinks API is applet-based, it is subject to the various implementation idiosyncrasies of the user's Java version. The most notable issue is a Web browser crash that can occur when the user leaves a Web page before the applet can fully load.
Configuration and administration. In environments where IBM WebSphere Portal uses a different directory for authentication than IBM Lotus Sametime, you will likely need external assistance to integrate the two with the STLinks API; discussing SSO in enough depth to resolve this challenge is a topic for another article."
In migrating and testing the new Web Connect API over STLinks, the most noteworthy change was a 58% reduction in time taken to attain awareness as well as a near 600% reduction in time to browse between pages. The architectural changes away from the STLinks applet make such reductions inherent. For specifics, read the article available in The UC View available now.