2017 me, emerging from DeLorean, to 1995 me:
So, this new 'Pentium' chip, turns out the whole 'speculative execution' road is a bit of a mistake. Yes it makes Doom faster but 22 years later all our computer systems are hacked each week by gangs of roaming cyber-criminals wearing vintage 80s micros as cosmetic jewellery on their leather jackets
1995 me (stuck in E1M2): Got it, Doom will get faster
2017 me: Did you even hear a word I said? I said the 80s are going to be fashionable again.
@alcinnz @natecull I read somewhere that the fix "only" slows down system calls. Kernel memory is mapped into app memory in order to speed up system calls on x86 OSes. Unfortunately, hidden bits of that memory, containing sensitive data, are accessible thorough an exploit involving speculative execution. Most system calls are for I/O, so that's where you're going to see the performance hit.