Have you tried telegram desktop to compare? I don't use whatsapp, but I have never had a performance problem with telegram desktop and I've been using it for years on underpowered machines. I usually run some variant of Debian on them.
Yeah, I'm sure that a lot of people notice the same thing then uninstall it. It's one of the solutions to the Fermi paradox, that both people have telegram installed at the same time.
