Yep, very likely. I keep Plugins disabled by default in Opera i
(Tools|Quick Preferences|Enable Plugins).

Flash causes a dramatic system slowdown and I have been plagued by
that over all versions of Ubuntu/Opera/Firefox.

I use Firefox when I have to view a website containing Flash and the
slowdown/increase in CPU load is noticeable. Often the CPU would max
out when a Flash enabled website is loaded

FWIW, I do think Steve Jobs is right when he blames Flash for unreliability
issues.