Firefox's memory appetite has some users up in arms, but according to one of the open-source browser's developers, that's part of the plan.

Complaints about Firefox's memory use, particularly charges that it "leaks" memory -- that it doesn't release memory once it's done using it -- had been circulating for some time before Ben Goodger, now employed by Google, but still a lead engineer on the browser project, posted an explanation on his blog Tuesday.

"What I think many people are talking about however with Firefox 1.5 is not really a memory leak at all. It is in fact a feature," wrote Goodger.

Goodger went on to describe how Firefox 1.5's Back-Forward feature caches recently-viewed pages so that they're immediately available when users click the Back or Forward navigational buttons.

"This can be a lot of data," Goodger said. "It's a trade-off. What you get out of it is faster performance as you navigate."

Firefox, said, Goodger, will cache up to 8 previous pages, depending on how much memory the machine has. A PC with 1GB or more will cache as many as 8 pages, while a computer with just 256MB or memory will cache only 3.

Goodger's explanation didn't sit well with every Firefox user. As of Thursday morning, more than 200 comments had been left on this blog, while at Slashdot, twice as many have opined.

Most of those complaints centered on Firefox's refusal to free up memory once tabs had been closed. "I have closed tabs down to a single tab and seen no improvement in memory usage," said one example comment to Goodger's blog.

As other writers rose to Firefox's defense, tempers flared. "Users don't want to hear it's because of a 'poorly coded webpage' or 'it's your flash plugin'. They just want to use a browser that doesn't leak memory like there is no tomorrow," wrote another user.