Improve performance by using shouldComponentUpdate

[linclark]

Currently, we are calling render on each message instance with each state change. This is a pretty big performance hit as the array of messages gets larger. If we used keys and shouldComponentUpdate, then only the messages that had changed would go through render.

For the key, we may want to add an autoincremeting ID in utils/messages.js

[bgrins]

So what is the component(s) that should have the shouldComponentUpdate implementation? And should it be comparing keys on the old and new messages?

[linclark]

We should be able to do the shouldComponentUpdate on the MessageContainer and it should just be able to check the repeat prop.

The key would be added where we create the array of messages.

[bgrins]

@pelmers is working on this one

[pelmers]

Some test-writing progress in #128

[linclark]

@pelmers thanks for posting the WIP, and I'm so excited to see the test in there! it will be great if we can get numbers on the kind of improvement this provides.

[bgrins]

Closed by #128