Performance is important because people use benchmarks to choose between vendors.

And even if it's <0.1%, there is strong "optimization mentality" in those companies (because perf matters) so it's unlikely to happen in the current climate.

It's high bandwidth but also high latency. If a page was cleared every time it was allocated, it would cause very unpredictable performance because the CPU would have to tell the GPU to clear memory and then wait for the GPU to finish before any other operations on the buffer could be done. This definitely isn't something that should happen for every allocated page. It might be acceptable if this happened only to pages previously used by other processes. But it would still be unpredictable and could cause unwanted stalls in the middle of a game session, for example.

Also note that memory bandwidth is typically the bottleneck in modern games.

The best place to do this would be in the browser, clearing out any textures and buffers before deallocating them if the contents are deemed private.

>because the CPU would have to tell the GPU to clear memory and then wait for the GPU to finish before any other operations on the buffer could be done

If you're doing write-only operations, the CPU can queue them behind the clear. If you do a read, then the CPU has to wait whether you clear or not.

Latency doesn't matter. Clearing can be slotted in with other operations, such as first use.