Disclaimer - I'm not an investment professional and this does not constitute financial advice - it's purely anecdotal.
I shifted my Pearl Assurance private pension back in May as I was sick of sub 3% returns.
I opened a SIPP with trustnet direct (low charges and fairly free choice of funds/trusts/shares - more or less limited to whats available on the UK market, so no NASDAQ directly).
A weekends research later, plus a good helping of my own prejudices/beliefs (that banking/finance sucks balls and that aging populations/Ebola/cancer/HIV/dementia/ad infinitum means good returns on healthcare/biotech for the foreseeable future). I invest the lump across 8 funds and 2 trusts.
6 months later I've averaged 16% growth (after fees) though if I had gambled it all in biotech/healthcare it would have been between 30 and 50% growth depending on how I split it - there were 2 of my choices that havent performed as well as I would have hoped (both having lost around 8.5%) but these are not short term holdings - I'll see if they pick up over the next 2 or so years then decide what to do with them.
So if your traditional private pension is tanking take control of it with a SIPP, chances of doing worse than the mutuals is low and you may hit the jackpot. The longer you have till retirement the more chance you have to make a difference to your retirement pot.