Add more swap, run bitcoind from git.
Doesen't swap wear the SD card?
(snip)
If you are concerned about swap wearing the SD card, just use a USB thumb drive or something to hold a swapfile instead.
I've worn out a few thumb-drives doing that back in the days when I used Knoppix (but those were fairly cheap thumb drives), better bet is a hard drive or ssd (not sure how good an idea the latter is) -- not as fast, but the RPi isn't that fast either.