Semaphore.social is a mastodon/fediverse web client. I've been using it without issue up to now and it has not updated recently. After a few hours running the CPU usage of Firefox becomes very high (25-50%) and the about:performance shows that it is due to this tab, which shows at values from 110 to 160% or thereabouts. I haven't noticed this before updating to Firefox 134.0 so I suspect it may be a Firefox regression. However I cannot work out what the cause is, how to fix it, or if I should file a bug on it. Any ideas on how I can fix this?