Playing these mods require the exact same specifications as the default campaign.
If your computer can't handle them, then it's clear that your computer does not meet the recommended requirements or simply throttling down from overheating. And then we're basically talking about 12 year old hardware. So maybe it's just time to get some new hardware.
Now the most important setting here is: rendering quality.
Always High or you simply won't see important stuff as it will simply not render.
Start by lowering all the other options first:
Texture resolution
Texture filtering
Shadow quality
SSAO quality
Put them on medium. If it's still unplayable, just get a new computer. Seriously. Because then we're clearly in the <1 TF processing ballpark from 15 years ago.