Varying download rate?

Hey Folks,

I’ve been on DH shared for some years. Right now building a new site that will feature lots of streaming educational videos. Which is presenting a new issue:

Streaming videos weren’t loading fast enough to play without buffering. (The videos are compressed fine for web streaming, played via up-to-date JWplayer)

So, I moved to VPS two days ago to see if that would cure it. It did not.

To test what was going on, I created a large ZIP file (2Gb), placed it in my DH FTP space, and tried downloading it from a couple different computers via web browers.

I was getting download rates between 100 to 300 kbps. Awful! (And not due to my local internet service, because it tests around 11mbps and we can stream other sites just fine)

After about five minutes, the large-file-download started to gain momentum, and eventually was downloading around 1200 kbps.

It was like the throttle opened up… after this, I’ve been test-streaming our videos just fine. So what caused the initial slowness? And how can I prevent the slowness from returning?

Any tips are greatly appreciated.
(p.s. my VPS use graphs are fine, very low, my previous sites are very low traffic, plenty of RAM&load available at all times)