Ticket #8024 (closed bug: fixed)
Sizzle Performance Regression
| Reported by: | rwaldron | Owned by: | |
|---|---|---|---|
| Priority: | blocker | Milestone: | 1.5 |
| Component: | selector | Version: | 1.4.4 |
| Keywords: | Cc: | ||
| Blocking: | Blocked by: |
Description
http://www.readwriteweb.com/hack/2011/01/jquery-upgrade-twitter.php
http://www.dustindiaz.com/about-that-slowness-on-twitter/
I just wanted to document these here, close if we have tickets
Change History
comment:3 Changed 2 years ago by danheberden
- Status changed from new to closed
- Resolution set to fixed
comment:4 Changed 2 years ago by john
- Priority changed from undecided to blocker
- Component changed from unfiled to selector
- Milestone changed from 1.next to 1.5
So yeah - this was from moving to using qSA in jQuery 1.4.3. qSA(".class") is slower than doing getElementsByClassName("class") (which is what Sizzle would use internally). Amusingly the case of jQuery(".class") would/has been always using qSA if possible so that would've been "slow" for them as well.
I've moved some perf improvements from jQuery into Sizzle and added a ".class" check and quickly use getElementsByClassName if it exists. This will help to make the code faster in all browsers (and for other projects that use Sizzle).
Please follow the bug reporting guidlines and use jsFiddle when providing test cases and demonstrations instead of pasting the code in the ticket.
That sounds strange to me as 1.4.3 specifically included an update to Sizzle to improve the performance of element rooted queries. Also the blog post on the 1.4.3 release documents improvements on the performance of .find. Maybe we need a jsperf test on this