Severe memory leaks in Safari 8 (OS X 10.10)

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After updating to Safari 8, I've noticed severe memory leaks with Google Sheets, with a tab left open in background going from 300MB to 9GB in an hour or so, rendering the laptop slow and pretty much unusable until I kill the corresponding tab. By disabling all used extensions and re-enabling them one by one I've pinned this down to Ghostery, could you please fix this?

I'm running Ghostery 5.4.1 on Safari Version 8.0 (10600.1.25).