What makes it "too slow"? And how do you know it's the framework that's slow, as opposed to the web app itself?
The advantage of Struts1 (now long obsolete) was that it was the first widely used MVC framework, and set the standard for request-oriented web frameworks for years. Its disadvantage was an over-reliance on wordy XML configuration files, which have fallen out of favor.
Struts 2 (not compatible with Struts 1) is not nearly as widely used as Struts 1 once was. I don't know what (if anything) distinguishes it over the multitude of other available frameworks.