http://www.phoronix.com/scan.php?page=news_item&px=MTUyMDQLougher is planning to get these SquashFS performance patches merged soon; it might be too late for Linux 3.13 but otherwise would be material for the Linux 3.14 kernel. The improvements to SquashFS in the Linux kernel include enhanced parallel I/O, multi-threaded decompression support using perCPU variables, directly decompressing into the page cache for file data, and other changes -- including the refactoring of the decompressor interface and code.
In the change to enhancing parallel I/O by allowing multiple decompressors, one example test done on the patch shows a system with two CPUs and 4GB of RAM going from taking 99 seconds to decompress four SquashFS file-systems to now taking just nine seconds! The multiple decompressor support for SquashFS right now though is hidden behind its own kernel configuration option (SQUASHFS_MULTI_DECOMPRESSOR).
The patch to directly decompress into the page cache for file data showed single-data decompression going from a 13 MB/s to now decompressing at 67 MB/s.
This is mildly exciting - sounds like it could have the potential to make TCL *even* quicker :-)