UPDATE: I removed my previous content from here because someone copy-pasted it into StackOverflow. Google “thought” I stole it from there and “accused” me of hosting scrapped content… StackOverflow removed the offending content as soon as I reported it, but I did not want to risk Google comparing my site to some cached version they may have, and it was all outdated anyway.
The current state of affairs for downloading PECL extensions for Windows is still suprisingly bad. The only way I found (other than building your own) was to browse this list. Some of the extensions there will have zip files with compiled dll extensions. The substring “ts” in the name means “thread safe” and you can figure out “nts” on your own 🙂