I'm actually surprised how slowly most tech companies shed staff. In general, it seems the industry is pretty hit-driven, and if you're attached to a good product that's still making money, there's rarely much attrition, even when perhaps there should be. Conversely, a lot of great people get let go when a product isn't working (misses the market or no sales). It all seems kind of arbitrary and random. It's a lot different than, say, a restaurant with really tight margins where you're a day away from getting fired if you aren't perceived to be pulling your weight.
Thought 2: if you’re getting let go for performance reasons in a bad time for the company, often they really don’t have performance gripes, but they don’t want to put up with unemployment or file a lay-off, so they let go people that can possibly be fired for performance.