TTFB for small images/files can be > 5 seconds

[ether6]

I have unfortunately been getting results such as this from this awesome page speed tester and others. This is really frustrating because I think I am doing everything in my power to speed things up, but I have the occasional file with a 4-6 second load time. In the example below, the icon_facebook_link.png is ~1.5k.

http://www.webpagetest.org/result/131120...1/details/

The result below is with the pagespeed module (https://developers.google.com/speed/pagespeed/module) active:

http://www.webpagetest.org/result/131120...1/details/

The file it typically chooses to wait on is often the facebook or twitter icon, which is interesting considering I have a dozen or so other png-24 icons on that page.

Any thoughts and/or help are appreciated. I scoured the forum for over an hour and couldn't really find much for this exact issue. BTW, running Drupal CMS on an Amazon EC2 instance with Bitnami Cloud Hosting.

[GreenGecko]

Are you using a micro instance? I think my watch has more power available than one of those...

I'd say that these delays are caused by external forces. Try running on a small instance and see if you still have the problem. My site ( which is on a VPS, but one of my own... ) runs a LEMP stack - Percona MySQL 5.6, PHP 5.4 - with ngx_pagespeed, and usually returns straight A's.

With pagespeed, have you tried the inline_images and inline_css filters - both of those should be converted ( also using memcached to store pagespeed stuff is a good idea )???

[robzilla]

When I call the icon_facebook_link.png directly from Chrome and reload a bunch of times, I also get a few longer load times among those. And when I loaded the full site, it hung on ui_arrow_designtools.png and drupal.js; probably on others at another try. I would first look into disk performance of your VM, if you can, and perhaps run an ab (ApacheBench) test on a static file to see what kind of variations in load time you get. This seems to be affecting the TTFB of your pages as well (ranges from 0.5s to 2.5s).

[ether6]

Thanks for the replies guys.

@GreenGecko
I ran a test with the mirco instance, switched over to the small instance, ran two tests, switched back to micro and ran another test, and the results were:

run 1 (micro): 10.2 s
run 2 (small): 4.8 s
run 3 (small): 3.9 s
run 4 (micro): 17.7 s

I did not experience any unusually long hang-ups on any files when running the small instance unlike the micro (7.8 s and ~15 s respectively). I'll check out the inline_images, inline_css. Not sure I fully understand what you are saying regarding memcached, but I'll look into it.

@robzilla
I've never really used Apache Bench, but following this tutorial (http://www.petefreitag.com/item/689.cfm) and running this command:

ab -n 1000 -c 100 http://etherblue.com/sites/default/files...k_link.png

I came up with what I think are fairly typical/good results (on the micro instance):

Server Software: Apache
Server Hostname: etherblue.com
Server Port: 80

Document Path: /sites/default/files/icon_facebook_link.png
Document Length: 1198 bytes

Concurrency Level: 100
Time taken for tests: 0.792 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Total transferred: 1431000 bytes
HTML transferred: 1198000 bytes
Requests per second: 1262.92 [#/sec] (mean)
Time per request: 79.182 [ms] (mean)
Time per request: 0.792 [ms] (mean, across all concurrent requests)
Transfer rate: 1764.88 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 1 2 1.7 1 9
Processing: 8 74 12.5 78 86
Waiting: 8 74 12.5 77 85
Total: 13 76 11.6 79 89

Percentage of the requests served within a certain time (ms)
50% 79
66% 80
75% 81
80% 82
90% 83
95% 85
98% 85
99% 86
100% 89 (longest request)