One is a Pinebook Pro, which is an RK3399 processor. Another is a Surface Go 2 with an Intel Pentium Gold Processor 4425Y.
The actual issue is that the video conferencing works, but trying to do anything else is just suuuper slow. Well, the Surface Go 2 is actually fairly good as long as I'm not touching the ZRAM. But, trying to share a window in Google Meet will always involve a lot of waiting. Firefox and Chromium seem equivalent on the Surface, but the Pinebook seems better in Chromium lately.
I can bare-bones most apps I use on these laptops, but for video conferencing it seems like I have to drag along a whole browser.
How long have you been using Kmail?
I tried maybe 3 years ago and I found it incredibly buggy. I've been using Thunderbird, but definitely wish there was a KDE or Qt-native mail app that did what I wanted.