On the surface, how long Dropbox takes to process your files should depend only on your Internet connection and the size of the files. Beneath the surface, there are several factors that can affect Dropbox's speed, including the type of Internet service you have, how Dropbox is configured on your computer and whether or not your computers are on the same network. In most cases, a small text file can be processed in a matter of seconds, but it might take up to 10 or 15 minutes on a bad day. It's with the large files that the underlying factors really come into play.

Internet Speed Limits

Most Internet service plans have different bandwidth limits, or speed limits, for uploading and downloading files. This isn't something you normally notice when surfing the Web because your computer downloads much more information than it uploads. However, if your download speed is 6 Mbps and your upload speed is only 0.6 Mbps, it means it will take ten times longer to upload a file to Dropbox as it will to download a file of the same size. You can use a free speed test service from Speedtest.net, Xfinity or AT&T (see Resources) to see how fast your upload and download speeds are.

Upload Throttling

By default, Dropbox lets you download files as fast as your computer can get them. Upload limits, on the other hand, are limited to 75 percent of your maximum bandwidth. If you're in a rush to get your file up onto Dropbox's servers as quickly as possible, you can turn off this limit in Dropbox's preferences. To find the bandwidth settings, right-click the Dropbox icon on your desktop system tray, select "Preferences" and then click "Bandwidth." Here, you can customize the upload and download speeds, including setting both to "No Limit."

Bypassing the Internet

If you are using the same Dropbox account on two devices on the same local area network, Dropbox can sync them much more quickly by bypassing the Internet. You still need an Internet connection for Dropbox to do this, but once it detects the devices are on the same network, it will point them to each other using its LAN sync feature. Both devices need to be on at the same time and, if you have advanced firewall settings on your router, you can't block TCP port 17500. If you are sharing a file with a friend or syncing between devices on two different networks, you will have to wait for the files to first be uploaded to Dropbox before you can download them.

Extra Considerations

The size of your files and the number of files you are uploading to Dropbox also affect how long it takes for them to be available. If many others are trying to use the service at the same time as you are, it may take longer than usual to process your files. This is the same type of server lag you sometimes see when trying to play an online game or log in to a social media website. To see the file transfer status, right-click the Dropbox icon on your desktop -- you'll then see a menu showing you what is being uploaded or downloaded, the current speed, how many files are remaining and how much longer it should take.