Huawei Nexus 6P owners besieged by bootloop issues recently got some relief in the form of a ramdisk modification from XCnathan32 on XDA Developers, and that fix has now been updated to help some of the performance woes that the original incarnation carried. The bootloop issue seemed to originated from the four larger, higher-performance BIG cores in the BIG.little architecture of the Qualcomm Snapdragon 810 processor that the phone runs on, so the original fix simply disabled the four BIG cores and had the phone run solely on the LITTLE cores. The problem was that the change caused a much harder hit to performance than it should have, and that is because it actually forced the phone to use only one core for all foreground tasks. XCnathan32 has fixed this problem, and published a new version of the mod that allows the use of all four little cores at all times, allowing for performance that's fairly close to a stock Nexus 6P.
Whether you flashed the original fix or not, the procedures for this new one are the same. Simply boot your device up into bootloader mode, then hook it up to a computer with ADB installed, and flash the ramdisk mod from the terminal using the command "fastboot flash boot [name of the file here]," with the full directory and name of the file in the brackets, unless you've used a CD command or opened up a terminal in the file's location. Once the phone is up and running again, XCnathan32 recommends flashing a modified version of the ElementalX kernel that he has prepared, which will enhance performance a bit more while still only using the four smaller cores.
If your phone has a locked bootloader, your only choice is to try to boot the phone up long enough to get into your settings, then the developer settings menu, and enable OEM unlocking. Some users have reported success from freezing their phones and others by heating them up, or letting the phones' batteries drain completely, then booting them. If you manage to get into the settings and make the change before the phone shuts down, just boot it into bootloader mode, hook it up to a computer with ADB set up, then use the command "fastboot flashing unlock," and you should be able to use the instructions above.