That depends on many factors.
The best way to test is it on Droplet side or on remote server side (the server where file you want is located) is download some file from another server.
Use some well known server, there are A LOT around the Internet. For example try wget on Ubuntu image, they should have fast servers. Find something other and try it.

If you get slow speed too, contact Support. We on community can’t help with things like this, so Support will be much more helpful.

Well if you don’t, that means your Droplet is working flawless and there are problems on remote server. DigitalOcean or you can’t do anything there. Some of problems could be: server location, latency, routing… As you see, nothing you or DigitalOcean can help with.