Do an audit of the memoization of the selectors.

**Update:** I renamed this issue to be more general, as this specific memoization tweak may not work, but the general principle stands.

**Original post:**
The selectors have a decent amount of churn as the symbolication information comes in. Not all derived data needs to be recomputed based off of new symbols. I found this especially true when computing stack timing by depth.

Something along the lines of this may work:

```js
import { createSelector, createSelectorCreator, defaultMemoize } from 'reselect';

export const getProfile = state => getProfileView(state).profile;

export getInitialProfile = createSelectorCreator(
defaultMemoize,
profile => 'threads' in profile
)(
getProfile,
// Memoize off of the profile here.
profile => profile
);
```

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-70)