We know. The extension was updated 2 days ago but we are on fire so new, awesome updates are silently rolled out on daily basis. There is a brand new extension in the Chrome Web Store and by now you should already have it.
The main difference between the old extension and the new extension is the performance. The new extension system is now cleverly augmenting all requests issued by the tools in the online Suite without the need to forward messages 3-4 times per request between the different layers of Chrome. I guess this doesn't mean anything to you if you are not familiar how it all works but the bottom line is that it is faster.
You should notice drastic improvements especially when using the Scanner. Now the Scanner is configured to do 100 parallel requests by default. This is an artificial restriction, so-to-say, and in the future we can increase this number drastically to add more performance.
The UI is also more responsive when the new extension system is in place. This is because we are doing a lot of work in the background, leaving more resources to the UI. Generally, everything should feel a lot more responsive.
The old extension system is still there for backwards compatibility. These improvements currently affect just Chrome. We are working on the Firefox extension next.