I don't work on files that large as a rule, but I will offer this bit of advice: DON'T directly convert to CS6 by opeing the CS3 .indd files inthe new version. Export to .inx and open that instead. We have plenty of reports of disaster with files that were converted directly. Not all files will fail, but those that do tend not to show any sign of trouble until a sudden complete loss after a lot of editing. Back up and keep versions on a regualr basis as you work, too.
Inter-document cross-refernces are likely to be very fragile, too, if you use them.
IDCS6 will work under 10.6.8 and 10.7.5, both of which I am using either at home or work.
Nevertheless, have been using CS6 for some files in excess of 1000pp and am not particularly impressed. So the file is somewhat workable I have to disable all features such as live preflight, GREP styles, the anti-aliasing on the type preview has to be turned off... feels like working in an early version of pagemaker. Forget about indexing the file I had, that had to be done by "cheating". Wrote about it a while ago but this was my experience: http://colecandoo.wordpress.com/2013/05/19/features-or-speed-why-not-both-indesign/
Any tips or hints to improve performance are appreciated.
Thanks to both of you. I have not used GREP before, and don't think I'll need to do that. However, indexing as well as figure management with InSeq plug-in (>1000 figs in last project), including cross document reference in book, and indexing and TOC are crucial. My projects are like science text books, so pretty vanilla layout, no fancy optical effects, but long documents and lots of linked files. I like to write in the final software, rather than work on text in Word, then format in layout program. The last 1300 pp book took 12 years to get to the printer including all the research. So long term stability is critical. As mentioned before, main data drive is a RAID1, then back up to RAID5, plus backup in secondary, physically separate locality.
Given that Adobe is going cloud, which is a positive no-no for me, there is little hope that Adobe will bring out a CS7 with better long document stability. I may stay in CS3 for now; I also consider switching to Quark.
It's ID's own cross-refs that are fragile between files. Commercial plugins, at least based on what is reported here, seem to be OK.
There is essentially no difference in basic long doc functionality between CS3 and any newer version currently, though there are plenty of improvements to the interface and layout tools that increase productivity in general. As far as when there might be improvements to things like footnotes or indexing, those will only happen in future releases of cloud versions. Perpetual licensing ends at CS6 and CS6 is now "feature complete" meaning no new functionality will ever be added.