Running gem on an "old" computer

I’m using gem version 1.1.1.

I’m trying to update some gems I have. I do “gem update gem_name” and
gem is stuck on:

Bulk updating Gem source index for:

It takes ages and trashes my swap space. I have only a limited amount of
memory (256 MB) and it seems that’s the bottleneck.

I remember having this problem before, in the days of gem 0.9. Upgrading
to 1.1.1 solved the problem, but I now see that the problem hasn’t
completely gone.

Is there a workaround for this?