What you call threads are known under Solaris as virtual CPUs (or strands).
Disabling virtual CPUs 0,3,7,11 seems to me an odd advice. Assuming the goal is to leave a single strand active per core, I would expect it to be something like 0,8,16,24 or if you have a 4 core CPU, or 0,9,16,24,32,40 with a 6 core model and 0,8,16,24,32,40,48,56 with the 8 core model.
Anyway, it is unclear what you are trying to achieve. In your first question, you stated you were using an ldom but you don't tell how many virtual CPUs are available to the ldom OS.
Are there multiple processes competing for the CPUs on your server ? What is its reported load during peak periods ?
Disabling CPU strands isn't really something you can expect to improve performance but more to reduce it.
If you happen to run the latest Solaris 10 (8/11) or Solaris 11, you might instead have a look at the
Critical Threads Optimization, although I'm not sure about its impact, if any, in your case.