(ANSWERED) Halifax ad crashes my Firefox

[MitchT]

After recently doing a total refresh of Firefox I was without an ad-blocker and happy to stay that way as everything was so much faster, but the Halifax ad which is currently on the site has caused my Firefox to freeze every time it's appeared, forcing me to do a 'force quit' (Mac) every time. Therefore, the ad blocker (a new, less CPU-hungry one) is back for the time being.