If you are looking for a lightweight, fast loading chat client for your Yahoo chat, you can give YahElite a try. YahELite is a full featured Yahoo chat client and compatible with all feature from yahoo chat, including voice and webcam feature. This chat client software loads quickly, runs fast and is considerate of your computers resources. Since YahElite uses only minimal resource of DLLs, it has less lag and smoother scrolling. When running it uses your memory typically less than 2 MB of RAM.
The nice feature I like from YahElite is ads free environment. It makes my chat season runs smoother than on Yahoo Messenger.