Sorry, I didn't mean to cause you embarrassment.
It's one of the minor irritations of computer software, that two quite different things have such similar names.
Java is a standalone programming language, which has nothing directly to do with browsers. Java programs can be embedded in web pages in much the same way as Flash videos are embedded, but they're still quite separate from the browser. When you install Java it's installed system-wide, and all browsers will normally make use of the same Java libraries. So Java performance shouldn't vary between different browsers on the same system.
Javascript however is specifically designed to add rich programmable features to web pages. The code which interprets the Javascript is built into the browser, and each browser has its own code, so Javascript performance does vary between different browsers on the same system.
The similarity of name derives from the fact that Javascript was designed to have similar syntax to Java, so the code which the programmer writes looks much the same.
Sorry about the lecture. I get carried away sometimes.