[daemin]

Is it actually using 25% of physical RAM, or just (25% of 6GB) of Virtual Address space (well actually 4GB address space for 32 bit applications/browsers).

Then again do you actually notice a slow down when you try to edit those photos? Have you run benchmarks to see if it's really a problem with RAM usage or if it's some Flash or other plugin that's gobbling up your CPU, hence the slow down.

Does that really matter so much, since if you actually need to use that Physical ram for your editing task the OS should page out physical memory from the browser and other unused applications and make it available for your needs.

[nitrogen]

It was a hypothetical scenario based on a combination of past experiences. Right now Firefox shows 464M resident (RES column in top) with five tabs open (wait, it's growing, now it's 480M, 486...). After a couple of hours it will be close to 1GB resident.

I've been working on large images in Gimp and Hugin/panotools in the past, and reached a point where swap was being used. The system immediately slowed to an unusable crawl with only a few % of swap in use. Considering that rotating hard drives have a random access throughput of a few MB/s, it's not surprising. These days a swap partition's only use is hibernating. Swap is effectively useless.

One webapp I'm working on triggered a bug in older versions of Chrome that caused it to grow rapidly in size, quickly consuming all of memory. Fortunately that was fixed.

So basically, I'd like to have another GB of image data in RAM before hitting swap (or whatever it is I'm working on), while still having my browser responsive.

[daemin]

I've had Firefox (versions 3 onwards) running for weeks at a time and only ever had it using between 400-500MB of RAM.

Another thing to check would be what kind of ad ons you had installed, since I would imagine that they could have quite a significant impact on memory usage and performance.