Is GAE Really GZipping My Content? Slow Response Times with GAE as CDN

Question

I am testing out Google App Engine as a free Content Delivery Network and it feels like it's taking a long time to serve up my content. I read somewhere that GAE gzips all of your content by default, that's the primary reason I'd like to give it a shot.

Why does this gae page take a say a half a second to download, while your typical stack overflow page downloads much faster even with a ton more content?

What am I missing here? All I have done is create an app and uploaded an image according to that tutorial, but content is being served very slowly it seems. Any suggestions? (Not considering Amazon or other CDNs right now, just looking for help with GAE).

Note: I am using Safari when I visit those links, maybe safari is causing problems?

Answer 1

If I use the Chrome 5 Developer tools, there is a tab called audit. If i click test, it mentions the content is not GZipped.

Answer 2

I don't see anything strange about the latency for your sample GIF. I think all GAE engine apps are hosted in the united states so using it as a CDN may not be perfect if your users are in Asia for example. Browser caching should take care of the issue for you so make sure that is set up correctly.

apachebench for your GIF:

Percentage of the requests served within a certain time (ms)
  50%    211
  66%    257
  75%    288
  80%    289
  90%    296
  95%    302
  98%    328
  99%    345
 100%    345 (longest request)

apachebench for the stackoverflow logo (sorry Jeff):

Percentage of the requests served within a certain time (ms)
  50%    372
  66%    373
  75%    373
  80%    373
  90%    374
  95%    376
  98%    384
  99%    384
 100%    384 (longest request)

Note that your image is 4 times the size of the SO logo and that if you would make a lot of concurrent requests I would guess that the GAE hosted version would handle the load a lot better.

Gzipping a GIF would be pointless (and plain wrong) since its already compressed.

Answer 3

You can also use the excellent YSlow plugin for Firefox. This will give you an A-F performance grade based on about twenty different measures including compression of page components.