According to this article, for the scientists speaking, "fast" means maybe as little as 12,000 years rather than 200,000 years.
"Something wiped out nearly all life on Earth more than 250 million years ago, and whatever unleashed this mass die-off acted much faster than previously thought, scientists said Monday. The extinction killed off 96% of life on Earth". this latest study is based on an analysis of zircon crystals in a geological formation in Meishan, China.
This study was done by a team of researchers from MIT and the Nanjing Institute of Geology and Paleontology.
Full Article:
http://www.ecns.cn/2014/02-11/100214.shtml