Optimizing Page Load Times

John Callender writes, "Google engineer Aaron Hopkins has written an interesting analysis of optimizing page load time. Hopkins simulated connections to a web page consisting of many small objects (HTML file, images, external javascript and CSS files, etc.), and looked at how things like browser settings and request size affect perceived performance. Among his findings: For web pages consisting of many small objects, performance often bottlenecks on upload speed, rather than download speed. Also, by spreading static content across four different hostnames, site operators can achieve dramatic improvements in perceived performance."

Comments

Re:Erm.. huh?

[mabinogi]

1.5Mbps ADSL.
5 Seconds to refresh the page on slashdot. That's just to getting the page to actually blank and refresh, there's still then the time it takes to load all the comments.
Sometimes it's near instant, but most of the time it's around about that.
Most of the time is spent "Waiting for slashdot.org", or "connecting to images.slashdot.org".
It used to be a hell of a lot worse, but I installed adblock to eliminate all the extra unecesary connections (google analytics, and the various ad servers). I didn't care about the ads or the tracking, it just bugged me that those things made my browsing experience slower.
I find it funny that this guy is suggesting spreading across multiple hosts, it's my completely unscientific and entirely anecdotal experience that the more host names the browser has to resolve to load the page, the longer it takes before you get to see anything.

I'm in Australia so there's a minimum 200 ms latency on roundtrips - five roundtrips and you've added 1 second to the rendering time. Approaches that add extra DNS lookups really aren't going to help. (Though the DNS lookups themselves aren't necesarily going to take 200ms - they could be much faster if they're in my ISPs DNS cache, or the could be longer if it's got to query them)

Re:HTTP Pipelining

[baadger]

This is NOT just Opera fanboyism, but Opera however *does* do pipelining by default (with a safe fallback)

Opera pipelines by default - and uses heuristics to control the level of pipelining employed depending on the server Opera is connected to

Reference

Re:Simulation software available?

[ggvaidya]

You could try using Sloppy. I've only ever heard about it because its programmer has a very nice page on getting a free Thwarte FreeMail certificate to work with Java WebStart, so this isn't a recommendation or anything. Looks pretty decent, though.

Re:HTTP/1.1 Design

[x2A]

The limit's not to do with your connection speed as such - it's to do with being polite and not putting too much drain on the server your downloading from.

Re:Erm.. huh?

[orasio]

User perception of responsiveness on interfaces has a lower bound of 200 ms. Some times even lower.

Just because 1 seconds seems fast, it doesn't mean that it's fast enough to stop improving.
When you reach that 200ms barrier, the interface has perfect responsiveness, a bigger interval is always perfectible.