Analyze exchange performance #2991

[sschiessl-bcp]

bitshares#2991

[VerevkinAlexander]

Please review intermediate results of exchange performance analysis.

1. Visual evaluation
   Steps to check:
   ● open http://localhost:8080/market/CNY_BTS
   ● open the console
   ● turn on Highlighting Component Updates in в React Developer Tools
   Results:
   ● Rerenderings mostly occur at some intervals (about 3 seconds) if you don't interact with the UI .
   ● Together with the rerenderings a new message comes to the console: MarketsStore.js:992 Construct limit orders 1.3.113_1.3.0: 4.919921875ms.
   ● The entire Exchange component is redrawn.
   ● Rarely there are single child components redrawn out of turn.

Many of the components have no changes in them (such as order creation forms or the empty My open orders list), so they may not be redrawn.

2. Profiling
   Steps to check:
   ● recorded a profile using the Chrome Performance Tab profiler

Results:
● The profile shows that renderings are repeated every 2.6 - 3.2 seconds. The period remains the same regardless of CPU performance.

● The profile shows which components are being redrawn.

● You can also see that all renderings begin with a message to the console: “Construct limit orders”

The screenshot below shows which components are being redrawn and at what intervals. AltContainer -> BindToChainState(ExchangeSubscriber) -> ExchangeSubscriber -> Exchange and their children are marked in red.
Green marks are given to BindToChainState(Footer) -> Footer and AltContainer -> NotificationStatic and their children.
The Construct limit orders message to the console is marked in blue.

3. The "why-did-you-update" library check
   I have tried to use the "why-did-you-update" library.
   It provides a list of unnecessary re-renderings.

[VerevkinAlexander]

As for "how many subscriptions do we end up with? (in ChainStore)" question.
Component “ExchangeSubscriber” subscribes to currentAccount, coreAsset, quoteAsset, baseAsset properties in ChainStore. "Exchange" component has 8 subscriptions. So in total: 12.