Word started trickling out about the beta of Vista SP1 yesterday and this morning, Long Zheng posts what I hope is good news. One of the fixes in SP1 will address the horrible disk thrashing that I’ve been reporting on when you use the ReadyBoost feature. (It led to me jettisioning ReadyBoost entirely.)

Robert Hensing, a security engineer at Microsoft, wrote on his blog about a performance flaw in ReadyBoost which severely hindered the responsiveness after resuming from standby (S3) or hibernate (S4) due to an architectural bug. The problem causes irregular and unnecessary hard-disk thrashing after resume which can take up to 8 minutes to settle down - ironically the outcome is the exact opposite of ReadyBoost’s purpose to increase responsiveness by caching. The cause is a simple yet stupid oversight in the design of ReadyBoost’s security system which encrypts all cache-data with an AES-128 encryption key, a great idea badly implemented.

Amazing that it has taken this long to find out this information that essentially cripples the ReadyBoost feature.