My colleague Scot Finnie has a surprising recommendation about Firefox 1.5: Don't.

Or, rather, not yet.

He's recommending against upgrading to the latest version of Firefox, at least temporarily.

That's surprising because Scot is, like me, a huge Firefox advocate. He loves it, and so do I.

Another reason it's surprising is because, back last month, Scot recommended the opposite.

So what's changed? Stability, compatibility and performance. Somewhere between the release candidate that Scot evaluated last month and the final version of 1.5 released two weeks ago, problems emerged. The new Firefox (he says) is slower and more prone to crashes than 1.0x versions. Moreover, there are more pages on the Web that are incompatible with the current version of Firefox than with 1.0x versions.

When I saw Scot's article, I sent him an E-mail. "I wish I'd seen your review before I upgraded last week. Thanks a lot, fella," I said.

But I was just giving Scot a hard time. My experience with Firefox is somewhat different from his. I'm finding 1.5 to be pretty stable. I haven't noticed any sites that are incompatible with Firefox 1.5 in the week I've been using it. As a matter of fact, there's one site I visit many times every day that never used to work with Firefox, and now does: the content-management system we use to run InformationWeek.com--although Scot says that parts of the CMS don't work with Firefox, and neither do some other applications on our company intranet that used to run just fine in Firefox.

As to stability: I have noticed that Firefox 1.5 crashes more often than previous versions, but it has only happened a couple of times during the week I've used it, so it's not important. Likewise, some pages seem to load slower in 1.5 than in previous versions, but not significantly more slowly.

So what's my recommendation on whether you should upgrade?

In the end, it's pretty much the same as Scot's: If you haven't upgraded to version 1.5 yet, then wait for the next minor update to do so. Version 1.51 (or whatever they decide to call it) will, hopefully, fix the problems we're seeing with 1.5.

On the other hand, if, like me, you have upgraded, then there's no reason to take the few minutes needed to uninstall the current version and reinstall the old one.

If I knew last week what I know this week, would I have still upgraded? Actually, yes. I like to run the latest version of software, even where there's no appreciable difference between the new version and the old one. I'm compulsive that way. Fortunately, like a neat-freak surgeon, I'm in a job that rewards that kind of compulsiveness.

Of course, Firefox is crippled without extensions, software add-ins that let you customize the browser's behavior. One of the most popular articles I've ever written was "My Favorite Firefox Extensions," which ran in April. After reading Scot's review yesterday, I took some time to look over the extensions landscape; read on to find out what I'm currently using and what looks intriguing.

EasyGestures: It lets you use your mouse--and just your mouse--to open a new browser tab, go back, go forward, copy a URL to the clipboard, refresh the page, bookmark a page in Firefox, open your bookmark oabek, and do a ton of other stuff. To do all this, you just press a user-customizable configuration of mouse buttons to open a circular, or "pie" menu, and select the option you want. (The default configuration is to activate EasyGestures with the center button of the mouse; I use a two-button mouse so I changed that to the right button.)

I used to use an extension called RadialContext, which was similar to EasyGestures, but much more limited in capabilities. But RadialContext menu isn't compatible with Firefox 1.5, and it doesn't look like it will be anytime soon. EasyGestures is 1.5 compatible, and it's much more powerful and flexible than RadialContext.

I love this extension so much, I want to marry it. I've only beeen using it a day, but, unless some hidden bugs emerge, I never want to be parted from it. When I die, I want to be buried with EasyGestures in my coffin.

Viamatic foXpose: Click a button, and this extension will display thumbnail images of all your open browser tabs, arranged in convenient tiled format. Click on one of the tiles, and the tab pops to the foreground. This is sort of like tiling windows on your desktop, but different.

Scot brought this one to my attention. When I tried it out, I shot him an e-mail that said, "DUUUUUDE, VIAMATIC FOXPOSE IS SOOOOOOOOOOOOOOOOOOOO K00000000000000000000L!!!!!" At my company, we like to keep communications on a professional level at all times. This one's a keeper, as long as it proves stable.

IE Tab: Opens an Internet Explorer session inside Firefox. For those of us who have to access Firefox-incompatible pages, this one sounds more useful than it is. You can make a list of URLs that are always accessed in IE Tab, but the problem is that list does not (currently) accept wildcard characters. So you can mark a single page, but not a whole directory on a site; you really need to be able to mark a range of pages to get full usefulness out of something like IE Tab.

Still, IE Tab is handy and it limits desktop clutter--instead of opening up a whole new browser window for IE, you just need to open an IE tab inside Firefox. And the gee-whiz factor is very high. So I'll probably keep IE Tab, and hope that it gets more powerful in future versions.

Del.icio.us. That's the name of both the Firefox extension, and the Web service it accesses. Del.icio.us is a community bookmarking service; you can use it to post your bookmarks to the Web and you can see what other people have bookmarked. Even if you don't partake in the community aspects, del.icio.us offers better bookmarks than the native Firefox bookmarks, and much, much better bookmarking than MSIE.

The del.icio.us extension to Firefox lets you easily post del.icio.us bookmarks, and read your own bookmarks and others. This one's a keeper.

By the way, Yahoo bought the del.icio.us service Friday.

SessionSaver: Saves browser tabs between sessions. Here's how it works: Open a few browser tabs. Close your browser. Re-open the browser, and you can resume surfing where you left off, with the same tabs open. Works after Firefox crashes, too. This one's a keeper.

Searchbar Autosizer: Expands the size of the search box in the browser toolbar as you type. Usually, the box is very small; as you type stuff it gets bigger. This one's a keeper.

Extended Statusbar: Adds information to your status bar--the bar at the bottom of the browser--showing speed of download, percent downloaded, how many images are on the page, and how many images remained to be downloaded. Slightly useful on a high-speed connection, moreso as the connection gets slower and more balky. It's not doing any harm, so it'll stay on my PC, at least for now.

How'd I Get Here: Displays the path of pages you clicked through to arrive at a particular page. Looks like a keeper.

GreaseMonkey: This one is an extension that allows you to run scripts, which act like extensions but are much easlier to write. There's about a million GreaseMonkey scripts, many of which customize the behavior of specific Web sites, like GMail, Yahoo Mail, and various popular Web forums. Here's the Greasemonkey scripts I use; all of them are keepers:

Check Range: Click a single checkbox in a row of checkboxes in a Web page. Then, while holding down the shift key, click another checkbox elsewhere in the row. All the checkboxes in between will also be checked. If you routinely do that kind of thing, the Check Range extension is handy; if not, then not.

IMDBAge: I'm an Internet Movie Database addict. When displaying an actor or actress's page, IMDBAge will automatically calculate the person's age, or, if the person is dead, the age they were when they died.

And that's my current roster. I'm constantly trying out new extensions, and getting rid of ones that don't work out, so if you ask me again in six months, you'll find that I'm still using some on this list, and I've stopped using others.

What Firefox extensions do you find valuable? Have you upgraded to Firefox 1.5? If so, are you finding it stable? Let us know in the comments field below.