Larry,
Performance is a complicated question. :-)
When speaking of swap we are talking two separate and distinct swaps:
1. Operating System swap
2. PI image data swapping
The OS swap is where Windows or Linux swaps out "unused" applications freeing up memory for active processes. On Linux this is a separate partition. In Windows this can be a separate partition, but is more usually c:\pagefile.sys (< Windows 8 ) or c:\swapfile.sys. Both of these benefit from being placed on SSD.
The PI swap area is as described in Mike's link. Performance can be maximized by placing this area on SSD or on a RAMDISK (which nowadays is easier to accomplish in Linux). However, that being said, As Juan pointed out in the link, the way Linux manages memory and disk caching makes PIs use of a swap file almost transparent. This is due to the way Linux buffer disk I/O. Basically, on a Linux system unused RAM is allocated to the disk buffers so there is not really much of a performance hit for the kind of image data swapping that PI does.
File system performance is also a factor, though with Linux's buffering strategy less so in Linux than Windows. On Linux you also have a much better selection of filesystems to choose from each with different performance characteristics. So, one could, for instance, use different partitions (drives) to optimize a data set for reading (say astrometric catalogs) as opposed to writing (swap or cache). For general purpose use in most cases XFS is the filesystem one should use on Linux, ext4 is the other standard choice, but is in aggregate a slightly worse performer than XFS. I would not recommend any other filesystems on Linux at this time (btrfs i think will eventually succeed XFS for performance use cases). XFS is one of the highest performing file systems, and luckily enough the most stable. There is plenty of information about this topic on the series of tubes; which can help you make an informed choice if you intend to optimize.
-esy
