there is a post http://mydellmini.com/forum/long-but...nce-t5326.html
on here somewhere referring to an anandtech hardware article on SSDs that you should read. all SSDs will slow down over time and there is no way to bring them back to pristine condition presently - this is due to the way the controller accesses the memory during read, write, delete and overwrite operations. the article explains it much more eloquently than i could but bottom-line, once an SSD
is written to, those pages in memory will be a bit slower as each successive write must first perform an erase for that page, then a write. when the SSD
is brandy new and the page is empty, the write happens quite fast - after you've written to all the available pages at least once, now every write operation must first be preceded by an erase operation, effectively slowing things down.
more explanation at the link.