She's right. I had memory problems with my game, and I noticed that snow made it really bad.
Things like this happened all the time. That purple blob in the first pic is supposed to be a penguin...

And from there it got worse...

... and worse.

I do have lots of downloads, graphics on the highest and all EP/SPs, so that has a lot to say, too.
Someone at Sim Oasis tipped me about a memory manager (Memory Improve Master) that empties memory which is not in use (a big problem about Sims 2 is that the memory doesn't empty effectively enough, but continues to build, and eventually the game crashes). I've not had such troubles after I started using it. Not tried it much with snow yet, but I've got a heavy lot I've been working on, and nothing of the above has happened yet (despite the fact that I was ingame for 4 days straight).
Depending on your computer, Seasons can work or not. Crappy PC = not a good experience...
My laptop managed everything up to FT (sort of), including Seasons and CC. But it was slow, and I did avoid snow and weather generally.
I downloaded a buyable version of the aspiration award (?) weather controller, which I use to control the weather. I set it to spring and sunshine, unless I actually need weather. Otherwise, weather just gets in the way for storytelling...