Off topic:Basic computer question: why does my computer slow AFTER running a script?

Question

[QVINTVS_FABIVS_MAXIMVS]

Hi All,

This is a basic computer question that could help enlighten a biologist turned data analyst.

I have a script that forks into 6 processes, my computer has 8 cores and 8GB of RAM.

After running the script and quitting my terminal, my computer is extremely slow. What's the reason behind this? How can I fix it?

I know this is probably a stupid question, but I'm curious.

Thanks