Disclosed herein are methods, systems, and software for handling secure transport of data between end users and content serving devices. In one example, a method of operating a content server includes identifying a content request from an end user device. The method further includes, responsive to the user request, determining a transmission control protocol window size and a secure layer protocol block size. The method also provides scaling the secure layer protocol block size to match the transmission control protocol window size, and transferring secure layer protocol packets to the end user device using the scaled secure layer protocol block size.