If you just want to check Firefox 6.0, use Mozilla Firefox Portable Edition

• http://portableapps.com/apps/internet/firefox_portable

Install Firefox Portable 6.0. It won't affect the current version of Firefox on your system at all.

Check and tell if its working.

Thanks for the reply, however FF6 Portable only seems to be available for Windows and not on MacOS.

In any case I wish to install the production version of FF7 or 6 to make sure it doesn't behave any differently as opposed to a portable version. If things look good I'll switchover completely.

I saw a random post that I could just drag the FF7/6 icon to the desktop, rename it differently from the existing FF3 that I have (instead of dragging it to the 'Applications' folder which WILL overwrite/upgrade to FF7/6) and then proceed to use it without causing any issues or overwriting anything.

Is this true? If so then at least it answers half of my question. There is another part regarding how the FF user profiles are being handled by both old and new FF installations that call it out.

@manophilo, you could try MultiFirefox for Mac.

http://davemartorana.com/multifirefox/

Direct Download link-

http://mff.s3.amazonaws.com/MFF2_latest.dmg

For any problems you have first read this-

https://github.com/themartorana/MultiFirefox#readme

A problem is there, but luckily a very simple solution also exists-

Problem: I am not able to install multiple FF versions. I have one instance installed (3.6.16) and when I download another one (4.0), open the DMG and drag the app to my applications folder, then I (still) get the prompt that says that there's already FF version and if I would like to overwrite it...

I tried putting FF 4.0 in another folder(Applications/FF4) -that works- but MultipleFirefox still only shows one FF version. (It's listed as just 'Firefox')

Solution - resolved it by renaming the firefox.app to firefox4.app and moving into the main apps directory. It looks like it won't pick up an installation of firefox inside apps subdirectory.

-> I haven't done it myself, but i think you can Install another Firefox version if you but make sure to install it a New/separate folder from your currently installed Firefox folder.

-> Profiles

• https://support.mozilla.com/en-US/kb/Profiles

Check and tell if its working.

Thanks for the redirect to MultiFirefox, it's mighty useful for those who need it and helps to cut down on multiple icons for different versions of FF.

As mentioned, simplest solution is to rename the existing FF in Applications before copying/dragging any new version to it.

Glad I'm able to safely parallel run both FF3+ and FF7 to see which one I'll use; to conclude I'm going to stick with FF3+(32-bit mode) in the meantime as FF7 (64-bit mode) uses about double the real/virtual memory! I read that FF7 was memory intensive but didn't know it would be this extreme. On the other hand the %CPU is lower when I run FF7 and that's the upside, along with some other improvements.

1Password FF browser extension works for both versions although if you switch between multiple versions of FF, things get kind of iffy as one version of the browser will disable the extension for the other FF version. Something to take note for those who wish to switch between FF versions often.

I use PCs not Macs, so things may differ slightly.

You mention one version of Firefox disabling extensions used by another version of Firefox. But in the OP you mention having multiple profiles, if you use a profile with a single version of Firefox that should solve the problem.

Developers are working on various improvements to how Firefox uses memory, and the diagnostic tools available from the UI, one of the developers N Nethercote blogs about these and you may find some of the blogs of interest: e.g. http://blog.mozilla.com/nnethercote/page/2/

@manophilo,

Are you using MultiFirefox now and don't have any problems with it?

@John99: You're correct, I'm currently loading all my profiles using both FF3+ and FF7 Beta so that I can compare the speed, performance and memory usage between the 2 versions. Reason being that most of my profiles contain many windows and each window contains numerous tabs (think 4-12 windows and each window possibly having an average of 10 tabs, which quickly adds up to massive memory drain). Due to the nature of my usage I have to do this instead of using a particular profile to an FF implementation. Often I am left with <100MB of RAM on my 4GB macbook pro, thus my seemingly inane attention to FF memory usage :)

@Swapnilrustagi: I've tried it and it works well so far, although the benefit is limited as I only have 2 implementations of FF on my machine. Great for developers with multiple versions though!

If you store the windows or tabs as a folder will that simplify matters ?

If you need to it is possible to open libraries from other profiles. It is also possible to open two versions and once and drag and drop between libraries.

I seem to recall that there may be something odd about Macs and how memory usage is recorded probably something I read in one of the blogs I linked to recently. I am not a Mac user so there is not much I can add to this conversation. Hope others can help you.