Here's the thing, Firefox bleeds memory, not simply uses a bunch of it. Once a tab or window is closed, FF won't return any RAM to the system. As a result, I'm rebooting this relic 2 or 3 times a day, maybe more. I'll run up against the 8GB available, and "eccentricities" begin to manifest themselves, and that assumes the browser doesn't straight up crash. However, after a restart, Task manager shows only about 1/2 system RAM in use even after relaunching FF, with all previous windows and tabs retained.
Speaking, of "eccentrics", I'm one of them. I always seem come up with different results, in comparison to other members. I'm also somewhat of a hoarder, especially with respect to PCs I've built over the years. A last count, I have 7, and a stack of boxes, which will hopefully become #8, in the not too distant future. So, I don't game, nor do I feel obligated to have one fearsome PC that requires me praying to it multiple times a day, in the direction of Redmond. So, "different, (not networked), horses for different courses", is my approach.
That fact that AV solutions do use system resources, is a blatant and patent statement of the obvious. One which has been well known over at least the past 2 decades. Only 2 of my PCs run it. One, is dedicated to the appreciation of female erotic art. Opera is my browser of choice for it, while AVG free is its AV. The other is strictly for email, banking, and making a nuisance of myself here at TechSpot and Quora. Here, Avira free is the AV of choice. The 3rd is for image editing and a file repository. The 4th, is waiting for me to summon the ambition to come up with a strategy for integrating at least 12TB of files, simply so I'll know where they are.
As for "Opera being a memory hog", my usage doesn't bear this out. I can have several windows open, with perhaps as many 200 tabs open on multiple windows, without a whimper of protest from the browser. (Although, it does give up the ghost and crashes dramatically, once every few months). This is an ancient Core 2 Duo E7x00 CPU. The only time I get "low memory warnings", is when I have too many windows open in Explorer. A right click, "close all windows", remedies the issue.
One thing that has to be considered is that the tabs in it are static, merely pages of thumbnails, not actively remaining in communication with a server. Opera puts unused tabs to sleep, and at least in my case, more effectively than FF's solution.
Both web machines run Windows 7, and despite dire warnings of doom, gloom, and verbal assaults on my intelligence, good old W7 works like a charm. I shut off updates at least 10 years ago. Some members crap their pants if they don't get a Windows update every half hour, I crap mine when I'm confronted with one.
It would appear that many of you have realized that, "M$ doesn't play nice with its users", preferring to use and abuse them. In fact, in a last ditch effort to dispatch any "malingerers" on Windows 7, M$ released a "final security update" for W7. What it accomplished was to make it impossible to navigate to even a site as benign as Walmart, without blowing up redirect warnings. Needless to say, the "wayback machine", (restore), earned its keep after that fiasco.
(IIRC, I changed my pants after that. Or did I? ICR)
To whom it may concern: I offer this post, not in any way to convince others to follow it as "advice". But rather as an explanation of my person preferences and procedures.