An anonymous reader shares a Tom’s Hardware report: Unfortunately, a default setting in Windows 11 Pro, having its software BitLocker encryption enabled, robs as much as 45 percent of the speed from your SSD as it forces your processor to encrypt and decrypt everything. According to our tests, random writes and reads — which affect the overall performance of your PC — get hurt the most, but even large sequential transfers are affected.
While many SSDs come with hardware-based encryption, which does all the processing directly on the drive, Windows 11 Pro force-enables the software version of BitLocker during installation, without providing a clear way to opt out. (You can circumvent this with tools like Rufus, if you want, though that’s obviously not an official solution as it allows users to bypass the Microsoft’s intent.) If you bought a prebuilt PC with Windows 11 Pro, there’s a good chance software BitLocker is enabled on it right now. Windows 11 Home doesn’t support BitLocker so you won’t have encryption enabled there.
To find out just how much software BitLocker impacts performance, we ran a series of tests with three scenarios: unencrypted (no BitLocker), software BitLocker (the Windows 11 Pro default), and with hardware BitLocker (OPAL) enabled. While the software encryption increased latency and decreased transfer rates, hardware encryption and no encryption at all were basically tied. If you have software BitLocker enabled, you may want to change your settings.