Site access unacceptably slow with captcha-bank plugin present

I just moved my site to a new host and was finding my wp access very slow. The progress bar would move a couple of cm and then stop for up to 60 secs before completing and loading the page.
Testing a non wp link to my site was nearly instant so it seemed it was something to do with wp. As I previously had issues with captcha-bank I logged in a deactivated it. Logged out and tried again. No difference.
I then logged out, removed the plugin entirely and logged in again.
Instant access. Not only to admin area of site, but to the site in general.
I replace the captcha-bank plugin and tried to access my site again.
60 secs!
Removed it, near instant.
For now I will do without the plugin.