You shouldn't disable Spectre mitigations, but Retbleed and Downfall (Intel) are much more of a "lab" exploit, and the fall-out for Retbleed is much more severe

You shouldn't disable Spectre mitigations, but Retbleed and Downfall (Intel) are much more of a "lab" exploit, and the fall-out for Retbleed is much more severe on cloud boxes than your personal PC. Easy 20-40% performance uplift on AMD Zen1-Zen2 and Intel 6th-11th gen.