Gigantic /var/vm folder - 26GB

You must be running a process with a huge memory leak. Don't delete the swapfiles -- that happens automatically when you reboot. Launch the Activity Monitor application and watch for processes whose memory allocation increases with time.

No. What matters is not the size but how it changes over time. You'll probably find that one process keeps growing and eventually dominates. It will almost certainly be a third-party application.

As I said, by watching how the memory allocation of the processes changes over time.

I don't think there's much point in my saying for a third time that you have to watch to see which process' memory allocation keeps growing indefinitely. There's no relationship between the amount of physical RAM installed and the size of the VM backing store.

If you are NOT running out of disk space, and you are not experiencing performance issues, then do nothing. Mac OS X is just doing its job.

NOTE: The sleepimage is ONLY used when you sleep your Mac. The pagefiles are used when you are running your mac. Since you have 8GB of RAM, your minimum /var/vm is going to be 8GB + 64MB, but that will grow over time as you run more concurrent applications.

The pagefiles will NOT go away on their own, only as a reboot. But what this means is that they indicate a peak memory usage, not your current usage. So if you have times during the day when you are either running a very memory intensive app, or lots more concurrent apps, then your pagefile usage will go up, and stay there. However, when you take a look, you may only be running a few apps that are not using all that storage, but the storage will remain in case you do need it again.

Your usage has created the pagefiles. If you are not out of disk space, do not worry about it. If you are running out of disk space, either get a bigger disk, find some files that you really do not need anymore (OmniDiskSweeper can help), or alter your computing habits so you do not need this much concurrent memory.

Something you are running is requiring all that current memory, way in excess of your 8GB of physical RAM. Only you can figure out what that is.

Watching Activity Monitor is generally something most people will not do on a regular enough basis to actually catch the offending set of applications.

You might try doing something like creating a shell script that runs the 'ps' command with the options needed to capture the RSZ (real memory size) information every 'n' seconds into a file. Then maybe you can go back and analyze the output to find the time period when all that memory was needed, and then hopefully identify the offending apps.

If you are a developer, is it possible the application you are developing is sometimes being a memory hog while you are debugging it?

Maybe it is just Xcode. I do not use it much, so I don't know how memory intensive it is. Then again, Xcode is more a collection of different apps that are run via Xcode, so it is also possible that Xcode will run lots of stuff in parallel that are fighting for memory.

Again, you are the only one that can tell what you are running, and analyze their memory usage.

If you are a developer, is it possible the application you are developing is sometimes being a memory hog while you are debugging it?

I hadn't thought of that. I'll bet that's the answer.

Not sure if the OP found the source of the issue, but I've got exactly the same problem in Lion. My /var/vm folder size is up to 26GB and I'm running with a 115GB SSD so it's filling all my available space.

The only 'big' application I use is Aperture but it would be good to know if there's a mechanism to manual clear the swap files or limit the maximum size of them?

This is a repost from another related thread. The problem gets reported in many places, but no-one ever joins the dots to illustrate that it is fundamental memory management bug in the OS.

......

This is an on-going and serious OS X bug. It is NOT confined to Lion, although that may have made it worse for some people. I experienced ths problem with Snow Leopard as well.

The problem is not with any particular apps, although it may start there. You can shut everything down on the system, and the swap will still not be freed. That's an OS X problem, because the processes that generated any memory leak have gone away, but OS X doesn't want to know.

The other symptom you will see is that the system will slow down dramatically, because activitymonitord is chewing up increasing percentages of CPU. I have seen activitymonitord running at over 40% of a CPU. That's impressive, and that was on Snow Leopard.

Apple needs to fix this, but they don't seem to be interested.