There are two parts to installing content. The first is the download from the DLS, which you are thinking of, and the other part has to do with the actual installation of content so this part isn't downloading the content.
What you are seeing here is the decompression of the Trainz Content Package (CDP) file and extracting the assets as well as installing them into your Trainz content. There are multiple processes which can affect the speed that this takes place. The process is quite CPU intensive due to the amount of processing, and if you have a base-spec model or slower processor, this will increase the time. The CDP size. Your 1GB file is quite huge and this will definitely take time as there's a lot of assets in there. As has been said each and every asset has to be decompressed, extracted, and installed.
And then there's the amount of disk space you have on your main drive. The content maybe installed on another hard drive or your main boot drive. On your boot drive is also temporary and swap files which will be created as the compressed file is decompressed and the assets extracted. This extra disk I/O is slow and if your disk doesn't have a lot of space on it, your computer is struggling to find space to extract the data.
To add insult to injury your drive could be fragmented so let's look at disk fragmentation. For regular hard drives which are fragmented, this will slow down your computer performance when it comes to stuff that requires disk I/O such as extracting files. Ensure your drives are optimized. For SSDs run the Trim command, which will occur if you attempt to defrag the drive with Windows 8 or Windows 10, or use the utilities for your SSD. For regular hard drives, this will defrag the drive and this process can take some time if you haven't done it before, or for a long time.
And finally what about your antivirus? I found that if I prevent my antivirus from scanning the Trainz content folders, actions such as installing and using content are substantially faster and less prone to stutters and hang ups. I'm not saying discontinue using your antivirus; just exclude your Trainz data folder and program folder from being scanned at real time.
John
PS: Sneaking in the forums to have a peek.
