v1.26.3.0 and v1.26.2.12 should not show off this behaviour any more on computers with low RAM amount since they got the "Allow Swapping" setting on by default and don't reset the camera view every second or so when the memory gets very low.
As for the swap file size, it's not directly linked to the usable virtual memory by a process: the usable virtual memory will also depend on the amount of RAM you got (since you can't use more non-swapped virtual memory than the amount of free RAM on your system) and on the OS (32 or 64bits, and in the former case whether it is configured to allow for more than 1Gb of virtual memory per process or not(*)). It is usually recommended to choose a size which is at least 1.5 times the size of your RAM (so, for 1Gb RAM, you could use a 1.5Gb or larger swap file).
One thing is certain: mesh viewers use 20% more memory than non-mesh viewers, and 1Gb of RAM is not really comfortable an amount for them...
(*) Under 32bits Windows (and provided you got more than 1Gb RAM), to benefit from the max 3Gb virtual memory usable by programs linked with the /LARGEADDRESSAWARE option (such as the Cool VL Viewer), you need to setup your boot loader options accordingly. I found a good description of the process
here.