I can vouch for the performance hit - I used to have a Surfacebook 2 and with Bitlocker enabled the machine was unusable. I’d say the performance hit was significantly higher than 45%. Turning it off at least allowed me to have a functioning laptop.

The same hardware then ran Linux with full disk encryption enabled and performance was night and day.

Being in the UK we miss out on all the benefits of the DMA but the Lawnchair project dropped an update a couple of weeks ago. It lets you change search providers and seems pretty stable and good enough for daily use.

GitHub - Lawnchair (Releases)