Google started using a new compression algorithm called “Courgette” to make Google Chrome updates small. It’s an anathema to us to push out a whole new 10MB update to give you a ten line security fix. We want smaller updates because it narrows the window of vulnerability. If the update is a tenth of the size, we can push ten times as many per unit of bandwidth. We have enough users that this means more users will be protected earlier. A secondary benefit is that a smaller update will work better for users who don't have great connectivity. Rather then push put a whole new 10MB update, we send out a diff that takes the previous version of Google Chrome and generates the new version, Chromium blog.