Performance Tracing

**No action needed yet (I need to flesh out):**

https://github.com/MetaMask/contributor-docs/blob/main/docs/performance-tracing.md

Initialization time
Display time
Signature time
Encryption time

For Extension and Mobile

Start with docs/performance-tracing.md in the contributor-docs repository, then review this issue's four timing areas: initialization, display, signature, and encryption. The scope still needs to be fleshed out for Extension and Mobile; this issue is ready only once the measurements and completion criteria are defined.

Written by the indexing model from the issue text.