I don't mind so much when a single program that I'm using interactively has a pause, even though it's annoying as hell. What really bugs me is that regardless of how many cores I have, there is always one pegged by that annoying background service. If I start up windows, you can bet that windows update will first peg a core for a few minutes. Then the builtin windows antiviris takes over (perhaps because win update wrote some files, who knows), pegging a core for a few more minutes. Then my backup program service (iDrive in this case) pegs a core for a few more minutes. All of these programs I understand why they are running, but despite me setting "quiet hours" and "please backup only at night" etc, they seem to run for several minutes when I least want it. After all these programs are done (or, I have killed their processes and stopped their services more likely), some completely random apps and services seem to always take a core and peg it. SNMP (some network protocol service) often does it for hours on end. Killing it doesn't make anything obvious stop working - so I have no idea why it can use 100% cpu for hours on end. Explorer.exe (the desktop process) often goes into 100% cpu-mode. The "sound graph isolation" service is a common culprit.
When doing normal desktop work, this is often barely noticable. But when I boot my windows machine, it's usually to play a game, immediately after startup. And despite having many cores to spare, if one core is pegged, the framerate is 20fps instead of 100fps. This is presumably not because of CPU starvation, but more likely because of competition for memory/cache/storage resources.
I don't understand how all these services must use 100% CPU for minutes, on a fast cpu core, and why they must run ANY logic on startup, which is when the user is most likely to use his machine. Don't even read your app config on start of process. Sleep a few hours and THEN wait until the machine is idle and THEN do logic! Using power save modes is no better. When you take it out of sleep after 12 hours, the services are very eager to check for updates or antivirus or backup again, regardless of time.
I wish windows could just let me use my machine for what I intend to - which is use ALL my cores for ONE foreground application, ONLY. I'd be happy to boot into a freaking "game mode" or "work mode" which is like safe mode and has ZERO crap running (no unnecessary services, no scheduled tasks can start and so on).