try less plugins in firefox. i only use ublock origin and numatrix (this can replace noscript and works better). don't enable too many filter lists in ublock, there's pretty severe impact.

or theres the choice of using chromium based instead. somehow they work much smoothly than ff. i still use kiwibrowser but it's discontinued so can't recommend it.. there's no ublock but cromite is decent

not sure wdym bluetooth backdoor tho. i personally don't use BT at all so..