Thanks for your replies, soenda and Steve.
I've been using psp since v.5 and it has been my photo editor of
choice since then. Funnily enough, I found v.9 a little more responsive
than v.8, but 11 and 12 have been very ponderous, and full of bugs, and
crashes for just about every reason thinkable, not just curves adjustment.
There haven't been many earth-shattering improvements/innovations
since v. 8, though, certainly not worth the upgrade price, in my opinion.
Despite using XaraXtreme Pro for most of my photo adjustments, there
are still a few things that psp does either better or more easily than Xara.
Being a relative novice with Xara, however, that may change as I become more and more familiar with it.
So I've kept psp x (10) on my system for a balance of speed, stability
and fairly recent features. Since Corel's acquisition, psp seems to be going the way of CorelDraw,
with subsequent releases being pushed out for no real good reason (as far as this punter is concerned).
Your replies have certainly helped me reach the decision to stick with
psp x for now.
Saludos,
Bob.