I‘m not sure. When my fiancée asked for help in speeding up her computer (a Compaq laptop) I ended up uninstalling a bunch of bloatware. She knew that having too much stuff installed was the root of the problem, but she was worried that removing stuff might break the computer in a way she wouldn’t be able to recover from.
In the end seeing as it was running Vista Basic I took the ultimate step of removing the OS as well and putting on Ubuntu, which she was much happier with :)
You can't blame the pre-installed bloatware when the PC is old. It's slow because it's old. It's gone through update cycles and has had software installed that slows it down.
(The whole question of windows needing occasional reinstalling is another issue)
In the end seeing as it was running Vista Basic I took the ultimate step of removing the OS as well and putting on Ubuntu, which she was much happier with :)