How to tweak boot time by disabling apple kexts (including cryptography related ones)?
If your corporation needs to comply with certain security standards you may have to use a FIPS 140 validated cryptographic module. If that is the case your company is likely to have an officer set aside to help you with that. (This will depend on the country you're located in.)

Removing any Apple supplied .kext modules will at best cause nothing or broken functionality in applications or at worst render your system unbootable. You certainly will not gain any improved boot times from removing any kext since these are loaded from a cached file anyway.

More info on Validated FIPS 140-1 and FIPS 140-2 Cryptographic Modules.

You don't specify how long your system's startup time is, but from my personal experience my MacBook Pro (6,1) takes less than 20s after entering the FileVault password to decrypt my boot partition. (SSD) Also I only reboot when I installed an update forcing me to do so which rarely happens so I personally consider boot times an absolute non-issue.

If your boot times are really way off the charts you cause is much more likely a damaged filesystem or dying hard drive/SSD than a problem with your kext cache.