I have tried both. I have Puppy Linux bootable on a USB stick. It is not noticably slow but every time I want to connect to a new Internet access point it is a struggle and almost one time out of two it does not save what was done in the computing session. Idk why. So it is fine for browsing but I can imagine working on a file with it. Also when you finally connected to internet and it doesn't remember it not cool. That's my (bad) experience. It doesn't means the problem come from the distribution.

It had someone install Mint for me on an old computer (10 years old) but it is quite slow. I have add it Libre Office but it is also slow to the point it discourage me to us it. But Libre Office has always be very slow for me whichever computer I used it on.

I don't know what to do to fix it. I consider myself computer-savy but as often with open source there is a lot of technical possibility and technical documentation but user experience and user documentation are an after thought.