Do you by any chance use the Twitter plugin for Contacts and Conversations? I didn't notice that it had infiltrated my SIP-only availability status, and as soon as I disabled Twitter, telepathy-haze stopped hogging the CPU.

If you can confirm, there's obviously a problem with that plugin. Luckily it's one I can live without. If it's not Twitter in your case, it might be a good idea to disable accounts one by one to find out which one is causing it.