Mods and cc certainly contributed to my old computer's end. I ran a cc-heavy and modded Sims 2 that made the night-day change every morning a gamble - would the game crash or not? Witches on community lots were another problem, they'd freeze the game regularly for several minutes, sometimes even to the point of crashing.
Now the interesting thing was that I was able to play a 25 sim household with no trouble when autonomy was off. With autonomy on the same household would crash after about half a real life hour of play. Apparently allowing the game to make decisions for my sims was much harder on my poor PC than adding a handful of fancy hairs. Since I normally play without autonomy, this allowed me to overload my computer with cc without suffering ill effects for several months. Good times! (To be fair, at that point I already knew I wanted to replace that PC, otherwise this would have been incredibly irresponsible, lol).
Nowadays I avoid most cc, especially alpha, and only take the objects in that I really need for my current saves. The rest waits in a folder I call "Seasonal cc" with subfolders by genre (Androids, Harry Potter, Oldwest etc.). My current mod count is 243 and I regularly check which of those potentially conflict with which others. If you curate your mods, look out for conflicts, keep them updated and learn which ones need to load in which order, I'd say mods are less damaging for your computer than high-poly cc.
