Myth file
“Windows is bloated and slow”
Verdict: It's complicated
Windows itself is fine. What manufacturers preinstall on top of it, and what Microsoft puts in the Start menu, is the real complaint.
A clean Windows install on decent hardware is quick and stays quick. The stereotype comes from two things that are not the operating system's speed.
First, OEM software. Cheap laptops ship with trial antivirus, vendor updaters and duplicate utilities that all launch at boot. Apple sells the hardware and the OS, so nobody else gets to preload anything.
Second, the advertising surface. Suggested apps, widgets and promotional tiles do not slow the machine measurably, but they make it feel like a device that is not entirely yours.
HouseCommentary
The house runs Windows and will still say it: advertisements in the Start menu of an operating system you paid for are indefensible. That is a different complaint from slow, and it is a fair one.