I got an answer from SanDisk support:
“The Extreme II SSD is shipped with latest firmware and there is no upgrade needed. The Slow wake-up from low power state is a known issue in the Mac OS 10.9 and it has been addressed in the latest update of OS Yosemite. Please verify that SMART status for the SSD in Disk Utility is “verified” and that you are not facing any other performance issue except slow wake-up.”
- no other suggested solution or work-around, just to wait for the next OS…
