Simon Willison’s Weblog

Items tagged performance

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rather baffling finding: POST requests, made via the XMLHTTP object, send header and body data in separate tcp/ip packets [and therefore,] xmlhttp GET performs better when sending small amounts of data than an xmlhttp POST

Iain Lamb # 18th August 2009, 12:27 pm

Memcached 1.4.0 released. The big new feature is the (optional) binary protocol, which enables other features such as CAS-everywhere and efficient client-side replication. Maintainer Dustin Sallings has also released some useful sounding EC2 instances which automatically assign nearly all of their RAM to memcached on launch and shouldn’t need any further configuration. # 17th July 2009, 10:26 pm

Firefox 3.5 for developers. It’s out today, and the feature list is huge. Highlights include HTML 5 drag ’n’ drop, audio and video elements, offline resources, downloadable fonts, text-shadow, CSS transforms with -moz-transform, localStorage, geolocation, web workers, trackpad swipe events, native JSON, cross-site HTTP requests, text API for canvas, defer attribute for the script element and TraceMonkey for better JS performance! # 30th June 2009, 6:08 pm

What’s New In Python 3.1. Lots of stuff, but the best bits are an ordered dictionary type (congrats, Armin), a Counter class for counting unique items in an iterable (I do this on an almost daily basis) and a bunch of performance improvements including a rewrite of the Python 3.0 IO system in C. # 28th June 2009, 3:02 pm

To Sprite Or Not To Sprite. CSS sprite images are decompressed to full bitmaps by browsers before they are rendered, so sprite files with large numbers of pixels will dramatically increase the memory footprint of your site. # 24th June 2009, 10:33 am

Django tip: Caching and two-phased template rendering. Neat trick for expensive pages which can be mostly cached with the exception of the “logged in as” bit—run them through the template system twice, caching the intermediary generated template. # 19th May 2009, 1:34 am

Loading Scripts Without Blocking. Steve Souders is publishing extracts from his new book, “Even Faster Web Sites”. Here’s a systematic study of different JavaScript loading methods, along with a decision tree for picking the most appropriate one for your application. # 30th April 2009, 7:56 pm

peeping into memcached. “Peep uses ptrace to freeze a running memcached server, dump the internal key metadata, and return the server to a running state”—you can then load the resulting data in to MySQL using LOAD LOCAL INFILE and analyse it using standard SQL queries. # 20th April 2009, 6:35 pm

ProjectPlan—unladen-swallow. A branch of Python 2.6 aiming to radically improve performance (the target is a 5x improvement), by compiling Python to machine code using LLVM’s JIT engine. I think this is a Google 20% time project (or maybe not, see the comments). An early version without LLVM is already available for download. # 30th March 2009, 10:09 am

Magic properties make Firefox synchronously load the Java plugin. Even defining a function called sun() (or several other symbols) will trigger the Java VM to be loaded, dramatically hurting the performance of your page. # 27th February 2009, 4:03 pm

jQuery 1.3.1 Released. Bug fix for 1.3, mainly browser compatibility issues. Of interest: jQuery no longer ship a packed version (where JS is used to further decompress a string), as their tests show that this reduces performance due to the overhead of the extra decompression. They still provide a YUI Compressor minified version. # 22nd January 2009, 10:41 am

Sloppy—the slow proxy. Java Web Start GUI application which runs a proxy to the site of your choice simulating lower connection speeds—great for testing how well your ajax holds up under poor network conditions. # 13th January 2009, 4:17 pm

simplejson 2.0.1. Python’s simplejson JSON library got a whole lot faster while I wasn’t looking. # 1st October 2008, 10:55 pm

Dromaeo: JavaScript Performance Testing (via) This is one classy benchmark. Run it in as many browsers as you like (each run is saved to the server and assigned a run ID), then compare the results by appending ?id=[run1],[run2]... to the URL. # 11th September 2008, 4:06 pm

TraceMonkey. Brendan Eich has been preaching the performance benefits of tracing and JIT for JavaScript on the conference circuit for at least a year, and the results from the first effort to be merged in to Mozilla core are indeed pretty astounding. # 22nd August 2008, 11:13 pm

ZeroMQ. Open source message queue optimised for performance: claims 25μsec latency and 2.6 million messages per second. # 27th July 2008, 4:57 pm

SquirrelFish. WebKit’s JavaScript engine was no slouch, but that hasn’t stopped them from replacing it with a brand new “register-based, direct-threaded, high-level bytecode engine, with a sliding register window calling convention”. It runs 1.6x faster and has the Best Logo Ever. # 3rd June 2008, 7:57 am

Yahoo!’s Latest Performance Breakthroughs. 20 new performance tips to join the previously published 14. Flushing the buffer while the backend code is still working to cause the browser to start loading CSS earlier is interesting. # 20th March 2008, 3:17 pm

IE8 speeds things up. Steve Souders notes that IE8 downloads script files in parallel before executing them sequentially, giving it a significant speed boost over other browsers that download sequentially. # 11th March 2008, 5:42 am

Nginx and Memcached, a 400% boost! Ilya Grigorik wrote up my current favourite nginx trick—you set nginx to check memcached for a cache entry matching the current URL on every hit, then invalidate your cache by pushing a new cache record straight in to memcached from your application server. # 11th February 2008, 10:05 pm

“Why doesn’t jQuery have an XPath CSS Selector implementation?” For now, my answer is: I don’t want two selector implementations—it makes the code base significantly harder to maintain, increases the number of possible cross-browser bugs, and drastically increases the filesize of the resulting download.

John Resig # 11th February 2008, 5:31 am

Announcing StaticGenerator for Django. Simple but powerful static file generator for Django applications—just tell it about your model instances and it will create an entire static site based on calling get_absolute_url() on each one. Uses signals to repopulate the cache when a model changes. # 7th January 2008, 9:26 pm

20,000 Reasons Why Comet Scales. Greg Wilkins coaxes Jetty and Bayeux in to supporting 20,000 simultaneous users per server while maintaining sub-second latency, using Amazon EC2 to run the benchmark. # 7th January 2008, 8:32 am

Ruby 1.9—Right for You? Dave Thomas on the just-released Ruby 1.9. It’s a development release that breaks backwards compatibility in a few minor ways, but new features include the YARV virtual machine (hence significant speed improvements) and unicode support via associating encodings with bytestrings. # 26th December 2007, 12:09 pm

ErlyWeb vs. Ruby on Rails EC2 Performance Showdown. ErlyWeb’s peak response rate beats Rails by 47x, albeit with a hugely simplified benchmark. More interesting than the results is the idea of using EC2 for benchmarking on identical simulated hardware. # 10th December 2007, 3:27 pm

Yahoo! Search Contextual Precaching. Neat performance trick on Yahoo! Search: the moment you start typing (indicating you intend to search) the site quietly fires off a bunch of requests to precache assets needed for the search results page. # 16th November 2007, 3:58 pm

CSS Sprite Generator (via) Upload a zip file of images and get back a CSS sprite plus a set of pre-calculated background image rules. Tool built by Ed Eliot and Stuart Colville for their forthcoming book “High Performance Web Site Techniques”. # 27th September 2007, 10:59 pm

YSlow. New extension for Firebug (yes, an extension on top of another extension) from the Yahoo! performance team which provides improved performance measurement tools and optimisation advice. # 25th July 2007, 4:48 am

Return of the HTTP overhead delay. Christian proposes a neat way of improving page performance, by delaying non-essential images such as avatars until after the rest of the page has loaded. # 11th July 2007, 3:12 pm

Reducing HTTP requests using make. Nice simple recipe for concatenating JavaScript in to one file using make—doesn’t do anything for cache-busting though. # 27th May 2007, 11:29 pm