Only minutes after posting my questions I found out that v2.0 stable had been released (and today
when running Secunia's security tool it has already labeled v1.1.8 as an end-of-life app
After installation, configuration, and a reboot (unrelated to SeaMonkey) v2.0 started quick enough
and memory use is still pretty good. No issues with general browsing, mail and news use.
At the moment though it won't replace my 1.1.8. The RoboForm Toolbar does not work with v2
and the RoboForm Bookmarklet (a neat workaround for unsupported browsers as well as for use
in Linux and Mac) doesn't work either but that may be due to NoScript (will disable and test later).
At the moment several extensions that work with 1.1.8 or even the 2.0 betas aren't ready for
2.0 stable like Mnenhy, Launchy, and PrefBar. So far I only have NoScript and FlashGot.
And I kind of liked the old Classic theme.
I use the Calendar extension with 1.1.8. Haven't checked if it's available for 2.0 but word has it
the latest Lightning beta may work.
Thanks for the tip regarding moving profiles as I do keep the profile in a non-standard location.