captainmoonlight has made me aware of an email he received from moonchild (Pale Moon dev):

A heads-up this time about the upcoming Firefox 10 release:
Pale Moon will skip the version 10 code base, considering the implemented
features in Firefox 10 are a (partial) implementation of web developer tools
that are of less significance, and it does not yet address the most important
issue currently present in Firefox, which is a massive performance issue for
animated images.
It is therefore not considered a relevant or significant release.
Of course, a point release will be made to Pale Moon 9 to implement critical security fixes once they are finalized in the Firefox source tree, and
possibly some other relevant patches will be implemented as well, to keep the browser safe and updated.
Version 11 shows more promise to be interesting and significant, with the
planned implementation of SPDY, the animated image fix (cairo) that has
plagued the browser since version 4 and for some reason was not considered top priority, and other, more complete implementations of features.
This will be on the menu somewhere in March of 2012.

For Pale Moon x64 users: I updated to 9.0.1 (and all’s fast and well) but noted the following on the download page:

“Many plugins are either not available or not officially released yet for 64-bit browsers. This will mostly hamper things like in-browser document viewers and media plugins. Most extensions (add-ons), however, do work, not to be confused with plugins.

Performance has been improved with this version but could possibly see some more improvements in the future as the x64 build process is still rather tricky to get to behave.” - http://www.palemoon.org/palemoon-x64.shtml

Thanks a lot for this tip, captainmoonlight. Getting better slowly, so I really appreciate the help, mate!