What I really like about XP is that when I click on Microsoft Word, it pops up immediately. It may take 1 second, but it's almost instant.

One second is not exactly instantly ...

On Linux, when I click on LibreOffice, I have to sit there and wait for half a minute for it to finally be ready so I can type.

Are you comparing apples and oranges? Linux is - strictly speaking - just an OS kernel, no graphical user interface. Linux distributions come with a wide range of GUIs. You can easily make a Linux distribution look like MacOS, Windows, or a Sun workstation. Or something completely different. Often, Gnome is the default. It is one of the GUIs that has a lot of fancy effects, is at least partially optimized for using with a touch screen, and I absolutely do not like it. It is fat, and slows down everything. But Linux gives you freedom of choice, just uninstall Gnome and replace it with something lightwhight, like Xfce. It looks like a desktop from the last century, but it also works well on hardware from the last century. Very limited visual effects, no "oh sorry, you have to wait for the end of this useless visual animation before resources for your desired action are available". And suddenly, your old computer feels fast again.

Alexander