My observations, using both Firefox (well, Iceweasel 20.0-1~bpo60+1), and Chrome (Chromium 26.0.1410.43-1). In many ways, I prefer Firefox as a browser (better plugins, controls, tabs, too much Google influence already).

My Firefox experience is getting to the point it's virtually unusable, with very, very slow response to any actions (especially new tab / new window functions). We're talking about many seconds, sometimes a minute or more.

While the overall footprint of Firefox is smaller than Chrome, Chrome's sandboxing of tabs gives vastly better user-based memory management: I've got the option of killing off tabs (without closing them) that are using excessive memory, restoring net system responsiveness.

Firefox uses a single process space, and slowness in one tab seems to extend elsewhere (my general observation, not based on analysis).

A larger part of the problem is a combination of how browsers facilitate (or don't) content management and browsing as a task and workflow, and the increasing emphasis on highly-interactive sites.

The lack of such tools, and especially the paucity of bookmarks as a management tool, means that my usual workflow management is:

- Open browser.

- Open lots of tabs. It's not uncommon for me to have 100s of tabs open across multiple browser windows.

For Firefox, Tree Style Tabs at least give some semblance of structure as to how I've traced down some link path. The flat horizontal tabs of Chrome absolutely suck in this regard. Having a better way to navigate the tabspace would help greatly.

What I've recently discovered, and what's radically changing my use of the Web, is Readability (Instapaper and Pocket are similar services). It's amazing. I've written a bit about this at Google+:
https://plus.google.com/104092656004159577193/posts/PhQR421e...
https://plus.google.com/104092656004159577193/posts/fVK7aJuB...

Readability solves three problems:

It renders web pages viewable. Far, far, far too many websites have designs which are overtly hostile to actually reading content (even HN, to some degree). Even those which are readable are far too distracting in the present ad-driven eyeball economy.

It manages my reading list. Rather than opening content in tabs, I append it to my reading list. Readability also offers tags (though limited to 500 per user, a wall I hit 2 days in) to help organize content (Firefox offers these for bookmarks, Chrome does not).

And the reading list is available across different browsers and devices (I'm not usually a fan of sharing personal information, least of all my reading interests, through a service, but in this case the convenience factor wins out).

Both of these factors could be addressed, somewhat, in a browser. I've been agitating for a while for a bifurcation of the browser space. Give me:

1. A browser primarily oriented at CONTENT. Simple, minimal page presentation (along the lined of Readability), focusing principally on core page content. With wide margins, high contrast, and a readable font face, and the ability to manage, organize, prioritize, sort, search, and cross-reference content.

2. A browser that is a highly-interactive application engine. Essentially today's Chrome (this fits with Google's long-term interests at replacing desktop apps).

We've mashed both of these under a single roof, and the fit's getting increasingly awkward.

Some things that would greatly help Firefox (and Chrome for that matter):

You do not need to have every tab loaded, rendered, in active memory and sucking CPU at the same time.

Give priority to the foreground tab. Close out background tabs (on a least-used / highest-footprint basis) and restore them when they're navigated to. The tab-switching hit should be bought back by overall greater browser performance.

Completely redesign bookmarks with thought given to workflow. The absolutely WORST UI attribute in any environment I've encountered across platforms is windows which cannot be resized, and bookmark management windows are horrible in this respect. I need MUCH more space to work with.

Improve responsiveness. One of the most painful aspects is how I interact with bookmarks. I can't open my bookmarks list, left-click a folder, and select "add page here" from a menu. Why not? DO NOT REPLICATE CHROME'S PLACEMENT OF "DELETE FOLDER" IMMEDIATELY ABOVE "ADD PAGE AND FAIL TO PROVIDE A DELETION CONFIRMATION DIALOG FFS!!!!!*

The existing "add page modal dialog is fucking annoying as hell* Half the time I want to refer back to the browser page itself to add information but the modal dialog blocks all browser page input.

Provide a duplicate entry search and reconcilliation.

Emphasize tags. They're present but poorly presented.

Emphasize bookmarks for navigation.

Improve annotation capabilities, including cross-referencing.

Provide a decentralized sharing mechanism. I don't care for SAAS generally on privacy basis, think FreedomBox. A low-overhead means to reference a resource from which I can post/recover my bookmarks from multiple devices and browsers would be useful.

Include a few lines of context from the page. Readability's "expanded* article view is excellent in this regard. Page titles almost always pretty much exactly suck. Though if you do this, provide both expanded and collapsed views.

ALLOW THE BOOKMARKS LIST TO WORK AS WORKFLOWS. "Date added", "date modified", and "last viewed" would be great. An "archive" flag is also useful (promote unarchived bookmarks up, allow viewing archived bookmarks if desired).

Provide the ability to download the bookmarks source in offline-readable format. Readability has the capacity to create ePub and Kindle content. Though it doesn't have a bulk-export tool (this would fucking completely absolutely rock my world).

Look at eBook management tools -- Moon+Reader, Calibre, etc. These are designed with libraries of content in mind. As antipatterns, look at Adobe Reader and PDF management in general (there is none) and avoid their worse mistakes, specifically: no management of archives, no bookmarking, no annotations, fixed-form-factor rendering, craptastic search, no tagging, poor zoom, very awkward in-document navigation, no cross-referencing capabilities.