With the full version of Firefox 3.6 due out in a matter of weeks, we thought we'd take a closer look at the most recent incarnation of Europe's favourite browser, and who better to lead us through than the director of Firefox development, Mike Beltzner.

"There are four things we ask ourselves at Firefox when we look to make change. Is it good for our users; that is, is it beneficial and easy? Can we do it quickly? Because speed is very important to people on the internet; we all only have a limited amount of time to do things. Can we do it securely and with respect to the user at the same time? And how do we deliver it to the consumer?"

Beltzner's words ring true. When you take a look at the core improvements to the browser this time around, many of the big changes are behind the scenes were the casual user may not notice them. When you look at the likes of Snow Leopard and Windows Phone, that kind of work seems to have been a theme for software this year.

"3.6 is 20% faster. That puts us multiple times ahead of IE8 but still a little behind Chrome". Much of this is to do with the update to the Gecko engine, now version 1.9.2, but stability has also been a big push for Firefox as well.

"We took a look at the stability of 3.5 and found that out of date plug-ins were the biggest cause of crashes. At their most extreme, they are exploitable. So, we've changed the way these load up so that the system can decide whether or not it will allow them to operate. If an out of date plug-in is found, we will direct you to the latest version on the internet or if necessary we can block it entirely".

On the front side of things, the famous Firefox tabs will now group together when from the same site, rather than opening up all the way over at the end of the line. There's still no task manager that details individual tabs, indicating which one might be causing problems - as you get in Chrome - but, according to Beltzner, it's something that's coming in 2010 with either Firefox 3.7 or 4.0.

Personas are the other big face-lift to the 3.6 software. What was previously an add-on to reskin your window has now been taken in-house as part of the core product.

"We didn't think it was exactly the computer programmers out there who were after this but we looked at the Personas add-on and saw it had been downloaded over 10 million times. We figured we could create something more nimble with one click to install and no restarting  Firefox".

This may not be the most exciting addition, but it's clear that there's bigger stews in the pot such as a stable 64-bit version of Firefox and a cleverer integration with Windows 7, such as getting Aero Peek to work for each individual tab too. All of this and more is bubbling away in the labs, promises Beltzner.

Of course much of what we see in one browser is often repeated in another particularly when successful. Tabs and quick dial front pages are the obvious ones to look at, features which appeared on Opera long before many others. The reason for the apparent plagerism is that  they all use each others software. They try them out.

"We look at other browsers and see what problems they solve. All of them are trying to minimise intrusion and there are questions like whether you want the tools open all the time when travelling around the web or whether a more minimal look is better, at the expense of having to spend the time opening the options up when you need them.

"Another issue is when is it okay or not okay to send information to our servers - as soon as people start typing in the address bar or only when they press enter? It's a speed vs privacy situation and we all choose different places on these lines".

The big question that's always itching to be asked to those in the browser game and, particularly Firefox, is how they feel like they're faring against the giant that is Microsoft, and Beltzner was good enough and philosophical enough to answer the question in full.

"It depends how you look at the metrics and how good you want to feel about yourself at the end of the day", he said with a wry chuckle. "It's an interesting question for us. In Europe, we have passed that majority mark, but our aim is to promote innovation and choice. What if we were that 90% company? Without the competition, could we make sure we were still doing that?"

"We're still in a world where a computer is a device that some companies wish to control. We don't care if users know the word browser or not, but it's about customisation for us. We want to help people use the web in the way they want it, and what we give them is a tool to do that".

"The web should not be what a single company says it is. It's a public place. It should be a resource".

We think it's safe to say that most people heartily agree.