Explore improving search performance to support high `maxResults`

extracted from https://github.com/microsoft/vscode/issues/8563#issuecomment-871226262

• open vscode repo
• have "search.maxResults": 200000000
• search for ;
• 🐌 notice how VS Code becomes slower and slower… I can see that each call to refreshAndUpdateCount takes close to 1 second and these calls happen repeatedly

[roblourens]

With the diffIdentityProvider, much improved:

Thanks for the tip @connor4312. And there are other easy optimizations to make on my end. With this many results, we can render less often or not at all. Nobody will read through 300,000 results, but we can keep them in the model for a replace.

[roblourens]

Not brave enough to make the needed changes for this release. Thanks @chrmarti