I don't know what Jane Street does, and can't speak for them. That being said, I've heard of some firms using the JVM that just tune things such that the garbage collector will never trigger, and then they restart the VM every night.
Unfortunately I don't have a citation for that. I think I've seen it talked about before here on HN before.
Even so, the deteriorated results I get from Google tend to be better than what I get anywhere else. I have DDG set as my default engine, and frequently need to fallback on Google.
I wish I could say DDG was as good or better, but outside of the privacy perspective, that unfortunately hasn't been my experience.
I suspect that, at least in places with decent internet, something like ShadowPC negates the need for such a service. I rent a top of the line gaming PC for ~$25/month, and run my games in the cloud.
With what I used to spend keeping a gaming rig upgraded, it doesn't even make sense not to rent something that's always going to be state of the art.
Unfortunately I don't have a citation for that. I think I've seen it talked about before here on HN before.