Mozilla executives today took shots at Google for pitching its Chrome Frame plug-in as a solution to Internet Explorer's poor performance, with one arguing that Google's move will result in "browser soup."

The Mozilla reaction puts the company that builds Firefox on the same side of the debate as rival Microsoft, which has also blasted Google over the plug-in.

Released last week, Chrome Frame lets Internet Explorer 6 (IE6), IE7 and IE8 utilize the Chrome browser's WebKit rendering engine, as well as its high-performance V8 JavaScript engine. Google pitched the plug-in as a way to instantly improve the performance of the notoriously slow IE, and as a way for Web developers to support standards IE can't handle, including HTML 5.

Specifically, said Google, it was pushing Chrome Frame because it decided it wasn't worth trying to make its new collaboration and communications tool, Google Wave, work with IE. Google developers spent "countless hours" on tweaking Wave for IE, but gave up.

"We could continue in this fashion, but using Google Chrome Frame instead lets us invest all that engineering time in more features for all our users, without leaving Internet Explorer users behind," argued Lars Rasmussen and Adam Schuck of Google's Wave team last week.

Mitchell Baker, the former CEO of Mozilla and currently the chairman of the Mozilla Foundation, disagreed with Google's tactic to slip Chrome inside IE. Strongly.

"The overall effects of Chrome Frame are undesirable," she said in an entry to her personal blog late Monday. "I predict positive results will not be enduring and -- and to the extent it is adopted -- Chrome Frame will end in growing fragmentation and loss of control for most of us, including Web developers."

According to Baker, Chrome Frame's browser-in-a-browser will confuse users and render some of their familiar tools useless. "Once your browser has fragmented into multiple rendering engines, it's very hard to manage information across Web sites. Some information will be manageable from the browser you use and some information from Chrome Frame. This defeats one of the most important ways in which a browser can help people manage their [Web] experience."