Your computer can display millions CAPTCHAs at once, but solving a million CAPTCHAs still takes ages because your solving speed is too slow, you are the bottleneck in this case.

Your computer can render hundreds megabytes of HTML and CSS within seconds, but you still need to wait minutes for a 10MB website to load when connection speed is poor, in this case the network is the bottleneck.

Windows 10 need to read a lot of data from disk and do some other works, on a computer with HDD only, it costs several minutes to load all the data needed, that's why replacing HDD with SSD improve Windows startup time significantly, in this case the HDD is the bottleneck.