The 2000s was a decade of great change in the computer industry. The world had grown accustomed to corruptible floppy disks, blue screens of death, and achingly slow load times. In a few short years, all of that would change, as USB drives, better operating systems, and faster processors brought forth a new age of stability and speed.

Amidst this era of upheaval, Microsoft introduced a new technology. It was intended to increase performance on the cheap to a new generation of machines, but it would turn out to be little more than a gimmick that never really caught on. Let’s explore the easily-forgotten legacy of ReadyBoost.

Boost or Bluster?

When Windows Vista was launched in 2006, it was built to make the most of new technologies that were rapidly becoming mainstream in the industry. Chief among them was flash memory. The USB flash drive had risen to prominence as a defacto solution for removable storage, while digital cameras and PDAs had made Compact Flash and SD cards familiar items to many.

Microsoft engineers realized that this presented an opportunity. While flash memory was still only available in relatively small capacities at the time compared to magnetic storage, it had a special advantage of its own. NAND flash could offer far quicker reads for random access compared to spinning magnetic hard drives, which were subject to the mechanical limitations of their rotational speed and how quickly their heads could seek across a platter. Thus, the idea for ReadyBoost was born—to use cheap flash storage as a cache to speed up random disk reads.

ReadyBoost had some basic requirements. It could only be activated on USB flash drives or other removable flash media with a capacity in excess of 250 MB. That was the minimum cache size, with a 4 GB maximum size in the initial Windows Vista release. One could decide to dedicate a device to ReadyBoost, or only use a segment of its total storage capacity.

Only a single device could be used at a time for ReadyBoost in Windows Vista, formatted in FAT16, FAT32, or NTFS. The drive in question would be tested to determine if it could achieve 2.5 MB/s read speeds for 4 kB random reads, as well as 1.75 MB/s write speeds for 512 kB random writes, in order to make sure it would be fast enough to work as a higher-speed cache. Similarly, access times had to be below 1 ms for the device to be of use.Any space used for cache could not be used for storing files. The ReadyBoost cache itself was stored as a file called ReadyBoost.sfcache.

ReadyBoost could be enabled on a range of flash media, as long as it met the above minimum specifications. USB flash drives were an obvious choice, if you didn’t mind having a dongle hanging off your PC or laptop all the time. Microsoft also noted that SD cards could be a convenient solution for permanently parking a ReadyBoost cache in machines that had a card reader slot. You could also use CompactFlash cards, too, if so desired.

Approaching the time of release, Microsoft engineers noted that random read performance on flash drives was 10 times quicker than hard disks. However, on larger sequential reads, HDDs were still going to outperform most USB 2.0 flash drives available. Even in 2006, it was noted that the ReadyBoost system would make the biggest difference under high disk use and low free memory conditions. On machines with lots of RAM and during light usage, it didn’t help as much.

ReadyBoost was just one of a range of technologies that was implemented in Windows Vista to aid performance. Microsoft also developed ReadyDrive, which was intended to hurry along boot times with the aid of newly-developed hybrid hard drives that combined magnetic storage with non-volatile flash memory. There was also SuperFetch, which assessed which applications were most commonly used and preloaded them into memory to allow them to load faster. These technologies were both a little more background in operation, though.

Microsoft gradually improved ReadyBoost over the years. Windows 7 brought upgrades, allowing the use of up to eight devices with a cache capacity of 32 GB each—putting the total cache size maximum at a hefty 256 GB. The algorithm behind ReadyBoost was also improved, while newer, faster flash memory and interfaces aided performance further. The technology persisted through later Windows versions, until it was eventually deprecated and eliminated in Windows 11 version 22H2. One suspects this was because use rates were so low that it didn’t make sense to maintain the feature any longer.

How much difference ReadyBoost did make in the real world? While the basis of the technology was sound, it’s not exactly clear how many users actually bothered to use it. The impact was theoretically greatest on systems with slower magnetic hard drives and low RAM. This became increasingly less relevant as the industry moved towards larger amounts of RAM and SSDs as standard. For most Windows users, it remains a footnote in the operating system’s history—an interesting curio that helped in some edge cases, but was perhaps not a gamechanger except for the weakest machines out there. In the end, it couldn’t compete with the tried-and-true method of just having faster primary storage and more RAM in the first place. It might have helped out a bit back when underpowered netbooks were struggling along and RAM in excess of 2 GB was a luxury, but today, ReadyBoost just doesn’t make sense when every PC out there has a blazingly fast SSD under the hood. The times changed, and the world moved on.